Nanocomposite, and optical member and backlight unit having the optical member

ABSTRACT

Disclosed is a nanocomposite. The nanocomposite includes a wax particle, at least one nano light-emitting body positioned inside the wax particle, and a silicon oxide protective layer for coating the nano light-emitting body. The nanocomposite can improve light stability and heat/moisture stability of the nano light-emitting body.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Korean Patent Application No. 10-2012-0126925 filed on Nov. 9, 2012 and Korean Patent Application No. 10-2013-0032896 filed on Mar. 27, 2013, and all the benefits accruing therefrom under 35 U.S.C. §119, the contents of which are incorporated by reference in their entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to a nanocomposite, and an optical member and a backlight unit having the optical member.

2. Discussion of Related Art

A nano light-emitting body including a quantum dot or the like is a material having a crystalline structure with a size of several to tens nanometers, and is constituted by hundreds to thousands atoms. Since a band gap increases as sizes of the nano light-emitting bodies are reduced even when the nano light-emitting bodies are formed of the same material, emission properties become different according to the sizes of the nano light-emitting bodies. In addition, the emission properties become different according to the used material even when the nano light-emitting bodies have the same size. The nano light-emitting bodies are variously used in various kinds of light emitting devices and electronic devices by adjusting such properties thereof.

However, since nano light-emitting bodies are very sensitive to ultraviolet light, heat, moisture, and so on, a lifespan of an electronic device may be reduced when the nano light-emitting bodies are applied to electronic devices or the like. In order to solve these problems, while methods of forming protective layers on upper and lower surfaces of a thin film including the nano light-emitting bodies to protect the nano light-emitting bodies in the thin film from ultraviolet light, heat, moisture, and so on have been proposed, it is difficult to completely prevent intrusion of the moisture into the thin film.

Meanwhile, a display device uses a white light source configured to emit white light in general. As the white light passes through a color filter, a user who observes the display device can see a color image. The white light source includes a blue light emitting diode (LED) chip configured to emit blue light, and a photoconversion substance configured to allow the light source to finally emit white light using the blue light. An yttrium aluminum garnet (YAG) phosphor is mainly used as the photoconversion substance. However, since the YAG phosphor has a wide emission spectrum throughout a red light wavelength band and a green light wavelength band, it is difficult to increase color purity of the color represented as the light generated by the white light source using the phosphor passes through the color filter, and color reproducibility of the display device may be decreased.

In order to improve the color reproducibility of the display device, in recent times, a variety of research on application of nano light-emitting bodies having an emission spectrum with a narrow full width at half maximum (FWHM) and high power density to display devices is being conducted.

SUMMARY OF THE INVENTION

In consideration of these problems, the present invention is directed to providing a nanocomposite capable of improving stability of a nano light-emitting body with respect to ultraviolet light, heat, moisture, and so on.

The present invention is also directed to providing an optical member, a diffusion sheet and a light collection sheet to which the nanocomposites are applied.

The present invention is also directed to providing a backlight unit to which at least one of the optical member, the diffusion sheet and the light collection sheet is applied.

A nanocomposite according to an embodiment of the present invention includes a wax particle, at least one nano light-emitting body and an inner protective layer. The nano light-emitting body is disposed in the wax particle. The inner protective layer coats the nano light-emitting body and is formed of silicon oxide.

In the embodiment, the inner protective layer may coat one nano light-emitting body. Unlike this, the inner protective layer may coat two or more nano light-emitting bodies.

In the embodiment, the nanocomposite may further include an outer protective layer. The outer protective layer may coat a surface of the wax particle and may be formed of silicon oxide. Here, the nanocomposite may include a wax layer formed on a surface of the outer protective layer and formed of a wax-based compound.

A nanocomposite according to another embodiment of the present invention includes a wax particle, at least one nano light-emitting body and an outer protective layer. The nanocomposite is disposed in the wax particle. The outer protective layer coats a surface of the wax particle and is formed of silicon oxide.

In the embodiment, the nanocomposite may include a wax layer formed on a surface of the outer protective layer and including a wax-based compound.

An optical member according to an embodiment of the present invention includes a base substrate, and a first optical layer disposed on one surface of the base substrate and in which at least one nanocomposite is distributed. The first nanocomposite includes a first wax particle, and at least one first nano light-emitting body disposed in the first wax particle.

In the embodiment, the optical member may further include a light diffusion layer formed on the first optical layer. Here, a light diffusion pattern may be formed on a surface of the light diffusion layer.

In the embodiment, the optical member may further include a second optical layer disposed on the other surface of the base substrate opposite to the one surface and in which at least one second nanocomposite is distributed. Here, the second nanocomposite may include a second wax particle, and at least one second nano light-emitting body disposed in the second wax particle. Here, the optical member may further include a light diffusion layer formed on the second optical layer, and a light diffusion pattern may be formed on a surface of the light diffusion layer.

In the embodiment, the optical member may further include a third optical layer disposed on the first optical layer and in which at least one third nanocomposite is distributed. Here, the third nanocomposite may include a third wax particle, and at least one third nano light-emitting body disposed in the third wax particle.

In the embodiment, at least one of the first to third nanocomposites may further include an inner protective layer or an outer protective layer formed of silicon oxide. The inner protective layer may coat a surface of any one of the first to third nano light-emitting bodies, and the outer protective layer may coat a surface of any one of the first to third wax particles. When any one of the first to third nanocomposites includes the outer protective layer, the wax layer formed of the wax-based compound may coat a surface of the outer protective layer.

In the embodiment, at least one of the first to third optical layers may include an optical pattern formed on a surface thereof.

A diffusion sheet according to another embodiment of the present invention includes a base substrate, and a first optical layer disposed on one surface of the base substrate, in which at least one nanocomposite is disposed, and having a light diffusion pattern formed on a surface thereof. The first nanocomposite includes a first wax particle, and at least one first nano light-emitting body disposed in the first wax particle.

In the embodiment, the diffusion sheet may further include a second optical layer disposed on the other surface opposite to the one surface and including at least one second nanocomposite. The second nanocomposite may include a second wax particle, and at least one nano light-emitting body disposed in the second wax particle. Here, a light diffusion pattern may be formed on a surface of the second optical layer.

In the embodiment, the diffusion sheet may further include an intermediate layer disposed between the base substrate and the second optical layer or between the base substrate and the first optical layer. Here, the intermediate layer may include at least one third nanocomposite, and the third nanocomposite may include a third wax particle, and at least one nano light-emitting body disposed in the third wax particle.

In the embodiment, the diffusion sheet may further include a second optical layer disposed on the other surface of the base substrate opposite to the one surface and having a light collection pattern formed on a surface thereof.

A diffusion sheet according to another embodiment of the present invention includes a base substrate, a light diffusion layer formed on one surface of the base substrate, and a first optical layer formed on the other surface of the base substrate opposite to the one surface and including at least one first nanocomposite. The first nanocomposite includes a first wax particle, and at least one first nano light-emitting body disposed in the first wax particle.

In the embodiment, the diffusion sheet may further include a second optical layer disposed on the first optical layer and including at least one second nanocomposite. Here, the second nanocomposite may include a second wax particle, and at least one second nano light-emitting body disposed in the second wax particle.

In the embodiment, the diffusion sheet may further include a light diffusion layer formed on the first optical layer.

A light collection sheet according to an embodiment of the present invention includes a base substrate, and a light collection pattern including a nanocomposite disposed on the base substrate and having at least one nano light-emitting body disposed in the wax particle.

A light collection sheet according to another embodiment of the present invention includes a base substrate, a light collection pattern disposed on one surface of the base substrate, and an optical layer disposed on the other surface of the base substrate opposite to the one surface and including a nanocomposite. Here, the nanocomposite includes a wax particle, and at least one nano light-emitting body disposed in the wax particle.

In the embodiment, a light diffusion pattern may be formed on a surface of the optical layer.

A backlight unit according to an embodiment of the present invention includes a light source, a diffusion sheet and a light collection sheet, and at least one of the diffusion sheet and the light collection sheet includes a wax particle, and one or more nanocomposites including at least one nano light-emitting body disposed in the wax particle.

In the embodiment, the light source may include a blue light emitting module.

In the nanocomposite according to the present invention, since the nano light-emitting body is protected by a wax-based compound or silicon oxide, light stability and moisture/heat stability of the nano light-emitting body can be remarkably improved.

In addition, according to the optical member and the backlight unit of the present invention, the color gamut of the display device can be increased using the nanocomposite, and color purity and color reproducibility of the color displayed on the display device can also be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which:

FIGS. 1A to 1C are views for describing a nanocomposite according to an embodiment of the present invention;

FIG. 2 is a view for describing a nano light-emitting body shown in FIGS. 1A to 1C;

FIGS. 3A to 3C are views for describing a nanocomposite according to another embodiment of the present invention;

FIGS. 4A and 4B are views for describing an optical member according to the embodiment of the present invention;

FIGS. 4C to 4G are views for describing various types of optical patterns;

FIGS. 5A to 5I are views for describing embodiments of a diffusion sheet according to the present invention;

FIGS. 6A to 6D are views for describing embodiments of a light collection sheet according to the present invention;

FIGS. 7A to 7C are views for describing embodiments of a light guide plate according to the present invention;

FIGS. 8 and 9 are views for describing a backlight unit according to an embodiment of the present invention;

FIG. 10 is an image for describing a color gamut of a display device including a backlight unit according to Comparative example 1;

FIGS. 11A to 11F are images for describing color gamuts of display devices including backlight units according to embodiments 1 to 6; and

FIG. 12 is a view for describing 9 points of a color coordinates uniformity estimation test.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may be variously modified and may have various shapes, and specific embodiments will be shown in the drawings and described below in detail. However, the present invention is not limited to the specific disclosures but all changes, equivalents and substitutions will be understood to fall within the spirit and the technical scope of the present invention. In the accompanying drawings, dimensions of structures are exaggerated or deemphasized for the purpose of clarity of the present invention.

While terms such as first, second, or the like, may be used to describe various components, the components are not limited by the terms. The terms are used only to distinguish one component from another component. For example, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component without departing from the spirit of the present invention.

The terms used in the application are not intended to limit the present invention but are merely used to describe specific embodiments. A singular form may include a plural referent unless the context specifically indicates otherwise. In the application, when an element is referred to as “comprising,” “including” or “having” something, it does not preclude other features, steps, operations, components, parts and/or combinations, but may further include other features, steps, operations, components, parts and/or combinations unless the context clearly indicates otherwise.

Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this invention belongs. Although preferred methods, techniques, devices, and materials are described, any methods, techniques, devices, or materials similar or equivalent to those described herein may be used in the practice or testing of the present invention. Structures described herein are to be understood also to refer to functional equivalents of such structures.

In the present invention, a wax-based compound is an organic compound that is in a solid state at room temperature and has a melting point higher than room temperature, and a wax particle is a regular or irregular particle configured by recrystallizing the wax-based compound and physically forming a monolithic body. Here, room temperature is a temperature within a range of about 15° C. to about 25° C. In addition, in the present invention, emission is a phenomenon in which electrons in the material are transitioned from a ground state to an excited state by an external stimulus, and then the electrons in the excited state are dropped to the stable ground state to emit light corresponding to a difference in energy between the ground state and the excited state.

In addition, in the present invention, a blue nanocomposite is a nanocomposite in which the nano light-emitting body is formed of only a blue nano light-emitting body. In addition, a green nanocomposite is a nanocomposite in which the nano light-emitting body is formed of only a green nano light-emitting body, and a red nanocomposite is a nanocomposite in which the nano light-emitting body is formed of only a red nano light-emitting body.

In addition, in the present invention, a multi-color nanocomposite is a nanocomposite in which the nano light-emitting body is formed of at least two kinds of nano light-emitting bodies selected from the blue, green and red nano light-emitting bodies.

The blue nano light-emitting body is generally a nano light-emitting body having an emission peak in a blue wavelength band of about 430 nm to about 470 nm, and the green nano light-emitting body is generally a nano light-emitting body having an emission peak in a green wavelength band of about 520 nm to about 560 nm, and the red nano light-emitting body is generally a nano light-emitting body having an emission peak in a red wavelength band of about 600 nm to about 660 nm.

Nanocomposite

FIGS. 1A to 1C are views for describing a nanocomposite according to an embodiment of the present invention, and FIG. 2 is a view for describing a nano light-emitting body shown in FIGS. 1A to 1C.

Referring to FIGS. 1A and 2, a nanocomposite 100 a according to the embodiment of the present invention includes a wax particle 110, and at least one nano light-emitting body 120 disposed in the wax particle 110.

The wax particle 110 is formed of a wax-based compound. The wax particle 110 may encapsulate the nano light-emitting body 120 to prevent damage to the nano light-emitting body 120 due to moisture, heat, light, and so on, caused by an external environment. In addition, as the nano light-emitting body 120 is disposed in the wax particle 110, the wax particle 110 may stably distribute the nano light-emitting body 120 in a resin to form a base substrate or an optical coating layer of the optical member.

In the present invention, encapsulation means that the nano light-emitting body 120 is disposed in the wax particle 110 and the nano light-emitting body 120 is surrounded by the wax particle 110. Here, Van der Waals force may be applied between the nano light-emitting body 120 and the wax particle 110.

A polymer, copolymer or oligomer typed synthetic wax may be used as the wax-based compound that constitutes the wax particle 110. For example, a polyethylene-based wax, a polypropylene-based wax or an amide-based wax may be used as the wax-based compound.

As an embodiment, when the wax-based compound is the polyethylene-based wax or the polypropylene-based wax, the wax-based compound may include at least one of monomers represented by the following chemical formula 1 to chemical formula 7.

In the chemical formulae 1 to 7, R₁, R₃, R₅ and R₇ may independently be a single bond or an alkylene group (*—(CH2)_(x)-*, x is an integer of 1 to 10) with 1 to 10 carbon atoms, R₂, R₄, R₆ and R₈ may independently be hydrogen or an alkyl group with 1 to 10 carbon atoms, and R_(a), R_(b), R_(c), R_(d), R_(e), R_(f) and R_(g) may independently be hydrogen or an alkyl group with 1 to 3 carbon atoms.

In a specific example, when R₂ of the chemical formula 1 is hydrogen, the monomer of the chemical formula 1 may include a carboxy group, and unlike this, when R₂ of the chemical formula 1 is an alkyl group having 1 to 10 carbon atoms, the monomer of the chemical formula 1 may include an ester group. In addition, when R₄ of the chemical formula 2 is hydrogen, the monomer of the chemical formula 2 may include an aldehyde group, and unlike this, when R₄ of the chemical formula 2 is an alkyl group having 1 to 10 carbon atoms, the monomer of the chemical formula 2 may include a ketone group. In addition, when R₆ of the chemical formula 3 is hydrogen, the monomer of the chemical formula 3 may include a hydroxy group, and unlike this, when R₆ of the chemical formula 3 is an alkyl group having 1 to 10 carbon atoms, the monomer of the chemical formula 3 may include an ether group.

When all of R_(a), R_(b), R_(c), R_(d), R_(e), R_(f) and R_(g) of the chemical formula 1 to 7 are hydrogen, the wax-based compound may be a polyethylene-based wax. For example, the polyethylene-based wax may be a polyethylene wax (a PE wax) including only a monomer of the chemical formula 7 in which R_(g) is hydrogen. Unlike this, the polyethylene-based wax may be the polyethylene wax further including at least one of oxygen-containing monomers of the chemical formula 1 to 6 in which R_(a), R_(b), R_(c), R_(d), R_(e) and R_(f) are hydrogen, besides the monomer of the chemical formula 7 in which R_(g) is hydrogen. For example, the polyethylene-based wax further including the at least one of the oxygen-containing monomers may include an oxidized polyethylene wax (an oxidized PE wax) which is an oxide of the polyethylene, an ethylene-acrylic acid copolymer, an ethylene-vinyl acetate copolymer, an ethylene-maleic anhydride copolymer, and so on.

In addition, when R_(a), R_(b), R_(c), R_(d), R_(e), R_(f) and R_(g) of the chemical formula 1 to 7 are independently a methyl group having 1 carbon atom, the wax-based compound may be the polypropylene-based wax. For example, the polypropylene-based wax may be a polypropylene wax (a PP wax) including only a monomer of the chemical formula 7 in which R_(g) is a methyl group. Unlike this, the polypropylene-based wax may be a polypropylene wax further including at least one of oxygen-containing monomers of the chemical formulae 1 to 6 in which R_(a), R_(b), R_(c), R_(d), R_(e) and R_(f) are hydrogen, besides the monomer of the chemical formula 7 in which R_(g) is a methyl group. For example, the polypropylene-based wax further including the at least one of the oxygen-containing monomers may include a propylene-maleic anhydride copolymer or the like.

In another embodiment, when the wax-based compound is an amide-based wax, the wax-based compound may be a polymer, copolymer or oligomer in which a main chain includes an amide bond (—CONH—). The amide-based wax may include a monomer having 1 to 10 carbon atoms. The amide-based wax may further include at least one of oxygen-containing monomers represented by the chemical formulae 1 to 6, besides the monomer having 1 to 10 carbon atoms.

When the wax-based compound includes the at least one of the oxygen-containing monomer of the chemical formulae 1 to 6, the wax particle 110 may more stably encapsulate the nano light-emitting body 120 than when only the monomer of the chemical formula 7 is included. This is because, when the wax-based compound includes the oxygen-containing monomer, interaction between metals of the nano light-emitting body 120 and the wax particle 110 is strengthened by polarity of oxygen contained in the oxygen-containing monomer.

When the wax-based compound includes a monomer having a carboxy group represented by the chemical formula 1 among the oxygen-containing monomers, the wax particle 110 is more advantageous for encapsulation of the nano light-emitting body 120, because the interaction between the wax particle 110 and the nano light-emitting body 120 is further strengthened. Accordingly, in the embodiment of the present invention, the wax particle 110 may be formed of the wax-based compound including at least the carboxy group serving as a substituent.

The wax-based compound that constitutes the wax particle 110 may have an acid value of about 1 mg KOH/g to about 200 mg KOH/g. In the embodiment, the acid value of the wax-based compound is the number of mg of potassium hydroxide (KOH) required for neutralization of the wax-based compound 1g. An amount of the carboxy group contained in the wax-based compound may increase as the acid value of the wax-based compound increases. When the acid value of the wax-based compound is less than about 1 mg KOH/g, the nano light-emitting body 120 may not be stably encapsulated because the amount of the carboxy group that interacts with the nano light-emitting body 120 is very slight. In addition, when the acid value of the wax-based compound is more than about 200 mg KOH/g, a surface of the nano light-emitting body 120 may be oxidized by the carboxy group. As a specific example, in order to stably encapsulate the nano light-emitting body 120, the wax-based compound that constitutes the wax particle 110 can have the acid value of about 5 mg KOH/g to about 50 mg KOH/g.

The wax particle 110 may be formed of a wax-based compound having a high density of about 0.95 g/cm³ or more. Since the high density wax-based compound having a high density of about 0.95 g/cm³ has a melting point relatively higher than a low density wax-based compound having a low density of less than about 0.95 g/cm³, a heat resistance of the nanocomposite 100 a including the wax particle 110 formed of the high density wax-based compound can be improved. In addition, since the high density wax-based compound has better crystallizability upon recrystallization than the low density wax-based compound, the wax particle 110 formed of the high density wax-based compound can more stably encapsulate the nano light-emitting body 120.

As a specific example, the polyethylene (PE) wax may be classified as a high density PE wax (an HDPE wax) having a density of about 0.95 g/cm³ or more and a low density PE wax (an LDPE wax) having a density of less than about 0.95 g/cm³, and the wax particle 110 may be formed of the HDPE wax. The density of the HDPE wax may be about 1.20 g/cm³ or less, and in this case, a melting point of the HDPE wax may be about 120° C. to about 200° C. On the other hand, a melting point of the LDPE wax may be about 80° C. to about 110° C. Accordingly, the wax particle 110 formed of the HDPE wax can improve the heat resistance of the nanocomposite 100 a according to the present invention more than that formed of the LDPE wax.

The wax particle 110 may be formed of a wax-based compound having a weight-average molecular weight of about 1,000 to 20,000. In the present invention, the weight-average molecular weight is an average molecular weight obtained by averaging molecular weights of component molecular species of a polymer compound having a molecular weight distribution with a weight fraction. When the weight-average molecular weight of the wax-based compound is less than about 1,000, since the wax-based compound cannot easily stay in a solid state at room temperature, it may be difficult to encapsulate the nano light-emitting body 120 at room temperature. In addition, when the weight-average molecular weight of the wax-based compound exceeds about 20,000, since a recrystallization size (an average diameter) of the wax-based compound is several hundreds of μm or more, even if the composite is manufactured using the wax-based compound, the wax-based compound cannot be easily distributed in a solvent or a resin. Further, when the molecular weight of the wax-based compound exceeds about 20,000, since the wax-based compound has a melting point of about 200° C. or more, the nano light-emitting body 120 may be damaged during a process of encapsulating the nano light-emitting body 120 with the wax-based compound.

A known nano light-emitting body may be used as the nano light-emitting body 120 with no limitation. For example, as shown in FIG. 2, the nano light-emitting body 120 may include a center particle 121, and a ligand 123 coupled to a surface of the center particle 121.

The center particle 121 may be formed of group II-VI compounds, group II-V compounds, group III-V compounds, group III-IV compounds, group III-VI compounds, group IV-VI compounds, or a mixture thereof. The mixture includes cases in which a dopant is doped in a ternary system compound, a tetrad system compound, or a mixture thereof, in addition to a simply mixed mixture.

Examples of the group II-VI compounds may include magnesium sulfate (MgS), magnesium selenide (MgSe), magnesium telluride (MgTe), calcium sulfate (CaS), calcium selenide (CaSe), calcium telluride (CaTe), strontium sulfate (SrS), strontium selenide (SrSe), strontium telluride (SrTe), cadmium sulfate (CdS), cadmium selenide (CdSe), cadmium telluride (CdTe), zinc sulfate (ZnS), zinc selenide (ZnSe), zinc telluride (ZnTe), mercury sulfate (HgS), mercury selenide (HgSe), mercury telluride (HgTe), or the like.

Examples of the group II-V compounds may include zinc phosphide (Zn₃P₂), zinc arsenide (Zn₃As₂), cadmium phosphide (Cd₃P₂), cadmium arsenide (Cd₃As₂), cadmium nitride (Cd₃N₂), zinc nitride (Zn₃N₂), or the like.

Examples of the group III-V compounds may include boron phosphide (BP), aluminum phosphide (AlP), aluminum arsenide (AlAs), aluminum antimonide (AlSb), gallium nitride (GaN), gallium phosphide (GaP), gallium arsenide (GaAs), gallium antimonide (GaSb), indium nitride (InN), indium phosphide (InP), indium arsenide (InAs), indium antimonide (InSb), aluminum nitride (AlN), boron nitride (BN), or the like.

Examples of the group III-IV compounds may include boron carbide (B₄C), aluminum carbine (Al₄C₃), gallium carbide (Ga₄C), or the like.

Examples of the group III-VI compounds may include aluminum sulfate (Al₂S₃), aluminum selenide (Al₂Se₃), aluminum telluride (Al₂Te₃), gallium sulfate (Ga₂S₃), gallium selenide (Ga₂Se₃), indium sulfate (In₂S₃), indium selenide (In₂Se₃), gallium telluride (Ga₂Te₃), indium telluride (In₂Te₃), or the like.

Examples of the group IV-VI compounds may include lead sulfate (PbS), lead selenide (PbSe), lead telluride (PbTe), tin sulfate (SnS), tin selenide (SnSe), tin telluride (SnTe), or the like.

For example, the center particle 121 may have a core/shell structure. Both a core and a shell of the center particle 121 may be formed of the exemplified compounds above. The exemplified compounds may be used alone or in combinations of two or more to form the core or the shell. While a band gap of the compound that forms the core may be smaller than a band gap of the compound that forms the shell, it is not limited thereto. However, when the center particle 121 has a core/shell structure, the compound that forms the shell is different from the compound that forms the core. For example, the center particle 121 may have a CdSe/ZnS (core/shell) structure having a core including CdSe and a shell including ZnS, or an InP/ZnS (core/shell) structure having a core including InP and a shell including ZnS.

As another example, the center particle 121 may have a core/multi-shell structure provided with a shell having at least two layers or more. For example, the center particle 121 may have a CdSe/ZnSe/ZnS (core/first shell/second shell) structure having a core including CdSe, a first shell surrounding a surface of the core and including ZnSe, and a second shell surrounding a surface of the first shell and including ZnS. In addition, the center particle 121 may have an InP/ZnSe/ZnS (core/first shell/second shell) structure having a core including InP, a first shell including ZnSe, and a second shell including ZnS.

As further another example, the center particle 121 is a single structure, which may be formed of the group II-VI compounds only or the group III-V compounds only, instead of the core/shell structure.

While not shown, the center particle 121 may further include a cluster molecule serving as a seed. The cluster molecule is a compound serving as a seed in a process of manufacturing the center particle 121, and the center particle 121 can be formed by growing the center particle 121 on the cluster molecule, using a precursor of the compound constituting the center particle 121. Here, various compounds disclosed in Korean Patent Laid-open Publication No. 2007-0064554 may be used as the cluster molecule, but the cluster molecule is not limited thereto.

The ligand 123 can prevent the neighboring center particles 121 from being agglomerated and quenched. The ligand 123 may be bonded to the center particle 121 and may have hydrophobicity.

As an example of the ligand 123, the amine-based compound, the carboxy group acid compound, or the like, having the alkyl group with 6 to 30 carbon atoms may be used. Examples of the amine-based compound having the alkyl group may include hexadecylamine, octylamine, or the like. As another example of the ligand 123, the amine-based compound, the carboxy group acid compound, or the like, having the alkenyl group having 6 to 30 carbon atoms may be used. On the other hand, as an example of the ligand 123, a phosphine compound such as trioctylphosphine, triphenolphosphine, t-butylphosphine, or the like; a phosphine oxide such as trioctylphosphine oxide or the like; pyridine or thiophene, and so on, may be used. The kind of the ligand 123 is not limited thereto, and if necessary, the nano light-emitting body 120 may be formed of only the center particle 121 without the ligand 123. The nanocomposite 100 a according to the embodiment of the present invention may have various shapes, and the one nanocomposite 100 a may have the at least one nano light-emitting body 120. For example, the one nano light-emitting body 120 may be disposed in the one wax particle 110, or unlike this, two to tens of millions of nano light-emitting bodies 120 may be disposed in the one wax particle 110.

For example, the plurality of nano light-emitting bodies 120 disposed in the one wax particle 110 may have the emission peak in the same wavelength band. That is, the nano light-emitting bodies 120 may include any one selected from a first color nano light-emitting body having an emission peak in a first wavelength band, a second color nano light-emitting body having an emission peak in a second wavelength band, and a third color nano light-emitting body having an emission peak in a third wavelength band.

The first color nano light-emitting body may be a blue nano light-emitting body having an emission peak in a wavelength band of about 430 nm to about 470 nm, the second color nano light-emitting body may be a green nano light-emitting body having an emission peak in a wavelength band of about 520 nm to about 560 nm, and the third color nano light-emitting body may be a red nano light-emitting body having an emission peak in a wavelength band of about 600 nm to about 660 nm. In this case, the nanocomposite 100 a may be referred to as any one of the blue nanocomposite, the green nanocomposite and the red nanocomposite.

As another specific example, at least two of the plurality of nano light-emitting bodies 120 disposed in the one wax particle 110 may have emission peaks in different wavelength bands. That is, the plurality of nano light-emitting bodies 120 disposed in the one wax particle 110 may include two selected from the blue nano light-emitting body, the green nano light-emitting body and the red nano light-emitting body. For example, the green nano light-emitting body and the red nano light-emitting body may be disposed in the wax particle 110. In this case, the nanocomposite 100 a may be referred to as a multi-color nanocomposite.

Meanwhile, a diameter of the nanocomposite 100 a may be about 50 nm to about 30 μm. The diameter may be defined as a value (a hydrodynamic diameter) measured by a dynamic light scattering (DLS) method of calculating the diameter using a Stokes-Einstein equation related to a diffusion coefficient.

Referring to FIG. 1B, a nanocomposite 100 b according to an embodiment of the present invention may include the wax particle 110, the at least one nano light-emitting body 120, and an outer protective layer 130. Since the nanocomposite 100 b is similar to the nanocomposite 100 a shown in FIG. 1A except that the outer protective layer 130 is further included, detailed overlapping description thereof will be omitted. A diameter of the nanocomposite 100 b may be about 50 nm to about 30 μm.

The outer protective layer 130 is formed on a surface of the wax particle 110 to coat the wax particle 110. The outer protective layer 130 is formed of silicon oxide (SiO_(x), 1≦x≦2). The outer protective layer 130 can prevent the nano light-emitting body 120 from being damaged due to moisture, heat, light, or the like, together with the wax particle 110.

The outer protective layer 130 may be formed through hydrolysis and a condensation reaction of a silicon oxide precursor material. For example, the outer protective layer 130 may be formed by mixing the wax particle 110 in which the nano light-emitting bodies 120 are disposed, the silicon oxide precursor material, a catalyst material and water in an organic solvent and growing silicon oxide on the surface of the wax particle 110. In this case, the outer protective layer 130 may include silica (SiO₂).

Example of the silicon oxide precursor material may include triethoxysilane (HTEOS), tetraethoxysilane (TEOS), methyltriethoxysilane (MTEOS), dimethyldiethoxysilane, tetramethoxysilane (TMOS), methyltrimethoxysilane (MTMOS), trimethoxysilane, dimethyldimethoxysilane, phenyltriethoxysilane (PTEOS), phenyltrimethoxysilane (PTMOS), diphenyldiethoxysilane, diphenyldimethoxysilane, or the like. In addition, the silicon oxide precursor material may be synthesized using a halosilane, in particular, a chlorosilane, for example, trichlorosilane, methyltrichlorosilane, ethyltrichlorosilane, phenyltrichlorosilane, tetrachlorosilane, dichlorosilane, methyldichlorosilane, dimethyldichlorosilane, chlorotriethoxysilane, chlorotrimethoxysilane, chloromethyltriethoxysilane, chloroethyltriethoxysilane, chlorophenyltriethoxysilane, chloromethyltrimethoxysilane, chloroethyltrimethoxysilane, chlorophenyltrimethoxysilane, or the like, or may be synthesized using polysiloxane, polysilazane, or the like.

Example of the organic solvent may include an alcoholic solvent such as methanol, ethanol, propanol, butanol, pentanol, hexanol, methyl cellosolve, butyl cellosolve, propylene glycol, diethylene glycol, or the like, or toluene. These organic solvents may be used alone or in combinations of two or more.

An alkali material, for example, ammonia (NH₃), may be used as the catalyst material. In this case, as ammonia water (NH₄OH) is mixed with the organic solvent, ammonia may be provided as a catalyst material in a process of forming the outer protective layer 130.

While not shown, the outer protective layer 130 can coat a plurality of wax particles 110. For example, the outer protective layer 130 can coat at least two wax particles 110 adjacent to each other, and the silicon oxide may be filled in a space between the wax particles 110 to form the nanocomposite. When a first wax particle and a second wax particle are coated with the outer protective layer 130, as the first nano light-emitting body disposed in the first wax particle has an emission peak in the same wavelength band as the second nano light-emitting body disposed in the second wax particle, the nanocomposite 100 b may be any one of the blue nanocomposite, the green nanocomposite and the red nanocomposite.

On the other hand, when the first wax particle and the second wax particle are coated with the outer protective layer 130, the first nano light-emitting body disposed in the first wax particle may have an emission peak at a different wavelength band from the second nano light-emitting body disposed in the second wax particle. That is, the nanocomposite 100 b may be a multi-color nanocomposite.

According to the above description, as the nanocomposite 100 b further includes the outer protective layer 130 in comparison with the nanocomposite 100 a described with reference to FIG. 1A, the nano light-emitting body 120 can be more stably protected from external moisture, heat, light, or the like.

Referring to FIG. 1C, a nanocomposite 100 c according to the embodiment of the present invention includes the wax particle 110, the at least one nano light-emitting body 120, the outer protective layer 130 and a wax layer 140. Since the nanocomposite 100 c is substantially the same as the nanocomposite 100 b described with reference to FIG. 1B except that the wax layer 140 is further included, detailed overlapping description thereof will be omitted. A diameter of the nanocomposite 100 c may be about 50 nm to about 30 μm.

The wax layer 140 coats the outer protective layer 130. That is, the wax layer 140 surrounds the wax particle 110 coated with the outer protective layer 130. The wax layer 140 is formed of a wax-based compound. Since the wax-based compound that forms the wax layer 140 is substantially the same as the wax-based compound that forms the wax particle 110, detailed overlapping description thereof will be omitted.

While FIG. 1C shows that the wax layer 140 coats the one wax particle 110 of which one surface is coated with the outer protective layer 130, the wax layer 140 can coat two or more wax particles 110. For example, while FIG. 1B describes that the outer protective layer 130 coats both of the first wax particle in which the first nano light-emitting body is disposed and the second wax particle in which the second nano light-emitting body is disposed, the surface of the outer protective layer 130 may be coated with the wax layer 140 again.

In addition, the wax layer 140 can coat at least two nanocomposites 100 b shown in FIG. 1B. As the wax-based compound that forms the wax layer 140 fills a space between the neighboring nanocomposites 100 b, the one wax layer 140 can coat the at least two wax particles coated with the outer protective layer 130.

The nanocomposite 100 c may be any one of the blue, green and red nanocomposites according to the kind of the nano light-emitting bodies 120 included therein, or may be the multi-color nanocomposites.

According to the above description, as the nanocomposite 100 c described with reference to FIG. 1C further includes the wax layer 140 in comparison with the nanocomposite 100 b described with reference to FIG. 1B, the nano light-emitting body 120 can be more stably protected from external moisture, heat, light, and so on.

FIGS. 3A to 3C are views for describing a nanocomposite according to another embodiment of the present invention.

Referring to FIG. 3A, a nanocomposite 200 a according to an embodiment of the present invention includes a wax particle 210, at least one nano light-emitting body 220 disposed in the wax particle 210, and an inner protective layer 230.

Since the wax particle 210 is substantially the same as the wax particle 110 described with reference to FIG. 1A and the nano light-emitting body 220 is substantially the same as the nano light-emitting body 120 described with reference to FIG. 2, detailed overlapping description thereof will be omitted.

The inner protective layer 230 coats the nano light-emitting body 220. The inner protective layer 230 may be in direct contact with the surface of the nano light-emitting body 220 to coat the nano light-emitting body 220. Here, the nano light-emitting bodies 220 disposed in the wax particle 210 may be coated with the inner protective layers 230, respectively.

That is, the one nano light-emitting body 220 may be coated with the one inner protective layer 230. The inner protective layer 230 may be formed of silicon oxide. The silicon oxide that forms the inner protective layer 230 is substantially the same as the silicon oxide that forms the outer protective layer 130 described with reference to FIG. 1B, detailed overlapping description thereof will be omitted.

The plurality of nano light-emitting bodies 220 disposed in the wax particle 210 may have an emission peak in the same wavelength band. For example, the nanocomposite 200 a may be any one of the blue, green and red nanocomposites.

On the other hand, at least two of the plurality of nano light-emitting bodies 220 disposed in the wax particle 210 may have emission peaks in different wavelength bands. That is, the nano light-emitting bodies 220 disposed in the wax particle 210 may include at least two of the blue nano light-emitting body, the green nano light-emitting body and the red nano light-emitting body. For example, the nanocomposite 200 a may be a multi-color nanocomposite.

While not shown, the inner protective layer 230 may coat two or more nano light-emitting bodies 220. When the two or more nano light-emitting bodies 220 are coated with the inner protective layer 230, a space between the neighboring nano light-emitting bodies 220 may be filled with the silicon oxide that forms the inner protective layer 230. Here, the nano light-emitting bodies 220 coated with the one inner protective layer 230 may have one emission peak in the same wavelength band. On the other hand, at least two of the nano light-emitting bodies 220 coated with the one inner protective layer 230 may have emission peaks in different wavelength bands.

Meanwhile, when the two or more nano light-emitting bodies 220 coated with the one inner protective layer 230 are referred to as an emission group, at least two emission groups may be disposed in the one wax particle 210. Here, one emission group may include first nano light-emitting bodies, and the other emission group may include second nano light-emitting bodies having an emission peak in a different wavelength band from the first nano light-emitting bodies. On the other hand, each of the emission groups may include at least two nano light-emitting bodies having emission peaks in different wavelength bands.

A diameter of the nanocomposite 200 a may be about 50 nm to about 30 μm.

According to the above description, since the nanocomposite 200 a has a structure secondarily encapsulated by the wax-based compound in a state in which at least one nano light-emitting body 220 is primarily encapsulated by the inner protective layer 230, the nano light-emitting body 220 can be prevented from being damaged due to external heat, light, moisture, or the like.

Referring to FIG. 3B, a nanocomposite 200 b according to the embodiment of the present invention may include the wax particle 210, the at least one nano light-emitting body 220, the inner protective layer 230, and an outer protective layer 240. Since the nanocomposite 200 b is similar to the nanocomposite 200 a described with reference to FIG. 3A except that the outer protective layer 240 is further included, detailed overlapping description thereof will be omitted. A diameter of the nanocomposite 200 b may be about 50 nm to about 30 μm.

The outer protective layer 240, which may be formed of silicon oxide, coats the wax particle 210. Since the outer protective layer 240 is substantially the same as the outer protective layer 130 described with reference to FIG. 1B, detailed overlapping description thereof will be omitted. The outer protective layer 240 can prevent the nano light-emitting body 220 from being damaged due to moisture, heat, light, or the like, together with the wax particle 210 and the inner protective layer 230.

While FIG. 3B shows that the outer protective layer 240 coats the one wax particle 210, the outer protective layer 240 can coat the plurality of wax particles 210. For example, the outer protective layer 240 can coat the two neighboring wax particles 210, and the silicon oxide may be filled in the space between the wax particles 210 to form the nanocomposite.

Referring to FIG. 3C, a nanocomposite 200 c according to an embodiment of the present invention may include a wax particle 210, at least one nano light-emitting body 220, an inner protective layer 230, an outer protective layer 240 and a wax layer 250. Since the nanocomposite 200 c is similar to the nanocomposite 200 b described with reference to FIG. 3B except that the wax layer 250 is further included, detailed overlapping description thereof will be omitted. A diameter of the nanocomposite 200 c may be about 50 nm to about 30 μm.

The wax layer 250 can coat the outer protective layer 240. The wax layer 250 is formed of a wax-based compound. Since the wax-based compound that forms the wax layer 250 is similar to the wax-based compound described with reference to FIG. 1A, detailed overlapping description thereof will be omitted.

The wax layer 250 may coat the one wax particle 210 having the surface coated with the outer protective layer 240 as shown in FIG. 3C, or may coat the plurality of wax particles 210 having the surfaces coated with the outer protective layer 240, although this is not shown.

According to the above description, as the nanocomposite 200 c encapsulates the wax particle 210 with the outer protective layer 240 and the wax layer 250, the nano light-emitting body 220 can be prevented from being damaged due to external heat, light, moisture, or the like. If necessary, a silicon oxide layer and a wax layer may be additionally and repeatedly deposited on the nanocomposite 200 c shown in FIG. 3C to manufacture the nanocomposite encapsulated with multiple layers.

Hereinafter, methods of manufacturing the nanocomposites according to the present invention as described above and stability estimation thereof will be described in detail.

Manufacture of Nanocomposite—1 [First Step]

After 20 mg of a wax-based compound was mixed with 1 ml of toluene, as a temperature was increased to about 150° C., the wax-based compound was dissolved to manufacture a wax solution. After a solution in which about 20 mg of CdSe-based red quantum dots (trade name: Nanodot-HE-606, QD solution Co. Ltd., Korea) was distributed in the 1 ml of toluene was mixed with the wax solution, the mixed solution was cooled to room temperature to manufacture a cooled solution in which about 10 mg of particles per ml of toluene were distributed. Here, as the wax-based compound, a wax (trade name: Licowax PED 136 wax, Clariant AG, Switzerland) serving as an oxidized high density polyethylene wax (an oxidized HDPE wax) having an acid value of about 50 mg KOH/g was used, and the particles distributed in the cooled solution included wax particles and red quantum dots disposed in the wax particles.

[Second Step]

After the cooled solution was added to the solution in which 10 ml of ethanol and 1 ml of tetraethoxysilane (TEOS, Sigma Aldrich Inc., US) were mixed, 2.5 ml of ammonia water having a concentration of 30% was additionally added to form the silicon oxide on surfaces of the particles, and the nanocomposite solution including the nanocomposite was manufactured.

[Third Step]

The nanocomposite solution was centrifugally separated using a high speed centrifugal separator at about 5,000 rpm for about 30 minutes to separate the nanocomposite and the separated nanocomposite was cleaned using ethanol and distilled water, and the ethanol and the distilled water were removed using an evaporator to manufacture a nanocomposite 1 in a powder phase.

Manufacture of Nanocomposite—2

The nanocomposite solution manufactured through the first and second steps described in ‘Manufacture of the nanocomposite—1’ was added to the wax solution including the wax-based compound. As the solution was cooled to room temperature to remove the toluene using the evaporator, a nanocomposite 2 in a powder phase having a wax layer formed on a surface of the silicon oxide layer was manufactured.

Manufacture of Nanocomposite—3

After the solution in which about 10 mg of CdSe-based red quantum dots (trade name: Nanodot-HE-606, QD solution Co. Ltd., Korea) was distributed in 0.5 ml of toluene was mixed with the solution in which 10 ml of ethanol was mixed with 1 ml of TEOS, 2.5 ml of ammonia water having a concentration of 30% was added to manufacture quantum dots having a surface on which the silicon oxide layer was formed. After the quantum dots were centrifugally separated using the high speed centrifugal separator at about 5,000 rpm for about 30 minutes, the quantum dots were cleaned with ethanol and distilled water.

Next, after 20 mg of the wax-based compound was mixed with 1 ml of toluene, the toluene solution in which the quantum dots coated with the silicon oxide layers were distributed was mixed with the wax solution manufactured by increasing the temperature to about 150° C. and dissolving the wax-based compound, and then the toluene solution was cooled to room temperature and the toluene was removed to manufacture a nanocomposite 3 in a powder phase.

Manufacture of Nanocomposite—4

The nanocomposite manufactured through ‘Manufacture of nanocomposite—3’ was mixed with the solution in which 10 ml of ethanol and 1 ml of TEOS were mixed, and 2.5 ml of ammonia water having a concentration of 30% was added.

Then, the solution was centrifugally separated using the high speed centrifugal separator at about 5,000 rpm for about 30 minutes to separate the nanocomposite, and the nanocomposite was cleaned using ethanol and distilled water. The ethanol and the distilled water were removed using the evaporator to manufacture a nanocomposite 4 in a powder phase.

Experiment 1 Estimation of Ultraviolet Light Stability and Heat/Moisture Stability

The nanocomposites 1 to 4 in the powder phase were prepared through the above-mentioned methods, and first quantum efficiency (QYT1, unit: %) thereof was measured using an absolute quantum efficiency measurement device (trade name: C9920-02, HAMAMATSU Photonics K. K., Japan). Next, after ultraviolet light (UV) having a peak wavelength of 365 nm was radiated at a radiation strength of about 1.4 mW/cm² for 480 hours, i.e., under severe conditions of about 2,419.2 J/cm², second quantum efficiency (QYT2, unit: %) was measured. A difference (ΔQY1=QYT1−QYT2, unit: %) between the first quantum efficiency and the second quantum efficiency was calculated to estimate ultraviolet light stability with respect to each of the nanocomposites 1 to 4. The result is shown in Table 1.

In addition, the nanocomposites 1 to 4 in the powder phase were prepared to measure first quantum efficiency (QYT1, unit: %), and then were left in a thermo-hygrostat under severe conditions of a temperature 85° C. and a relative humidity 85% for 480 hours. Next, third quantum efficiency (QYT3, unit: %) of the nanocomposites 1 to 4 after being left under the severe conditions were measured. A difference (ΔQY2=QYT1−QYT3, unit: %) between the first quantum efficiency and the third quantum efficiency was measured to estimate heat/moisture stability with respect to the nanocomposites 1 to 4. The result is shown Table 1.

TABLE 1 Ultraviolet light stability Heat/moisture stability Classification (ΔQY1, %) (ΔQY2, %) Nanocomposite 1 5.5 7.3 Nanocomposite 2 6.7 5.8 Nanocomposite 3 2.8 5.9 Nanocomposite 4 3.3 4.2

Referring to Table 1, it will be appreciated that the ultraviolet light stability with respect to the nanocomposites 1 to 4 is 6.7% or less, and the heat/moisture stability is 7.3% or less. A small value in the variation (ΔQY1) of the quantum efficiency due to the ultraviolet light radiation under severe conditions (a radiation amount of about 2,419.2 J/cm²) indicates improved stability with respect to the ultraviolet light. A small value in the variation (ΔQY2) of the quantum efficiency due to severe conditions of a high temperature and a high humidity (a temperature 85° C. and a relative humidity 85%) indicates improved stability with respect to the heat and moisture.

In consideration that the ultraviolet light stability with respect to the nanocomposite (see FIG. 1A) having the nano light-emitting body coated with the wax particles only is about 15% and the heat/moisture stability is about 16%, it will be appreciated that the nanocomposites including both of the wax particle and the silicon oxide like the nanocomposites 1 to 4 have improved ultraviolet light stability and heat/moisture stability.

Optical Member

FIGS. 4A and 4B are views for describing an optical member according to the embodiment of the present invention.

Referring to FIG. 4A, an optical member 501 according to the embodiment of the present invention includes a base substrate 510, and a first optical layer 520 in which at least one first nanocomposite CX1 is distributed.

The base substrate 510 may include a light incidence surface through which light enters, and a light emission surface opposite to the light incidence surface through which the light that has entered is emitted. The base substrate 510 is formed of a transparent material through which light passes. Examples of the transparent material may include a polymethylmethacrylate (PMMA) resin, a polycarbonate (PC) resin, a polyimide (PI) resin, a polyethylene (PE) resin, a polypropylene (PP) resin, a methacrylic resin, a polyurethane resin, a polyethylene terephthalate (PET) resin, or the like.

The first optical layer 520 may be formed on one surface of the base substrate 510, i.e., the light incidence surface or the light emission surface. The first optical layer 520 is formed of a polymer resin and the first nanocomposite CX1. The polymer resin is a matrix material of the first optical layer 520, and the first nanocomposite CX1 is distributed in the polymer resin.

The first nanocomposite CX1 includes a first wax particle, and at least one first nano light-emitting body disposed in the first wax particle. For example, the first nanocomposite CX1 may have substantially the same structure as the nanocomposite 100 a described with reference to FIG. 1A.

In addition, as described with reference to FIGS. 1B, 1C, 3A, 3B and 3C, the first nanocomposite CX1 may further include an outer protective layer that coats a surface of the first wax particle, or an inner protective layer that coats the first nano light-emitting body. When the first nanocomposite CX1 further includes the outer protective layer, the first nanocomposite CX1 may further include a wax layer that coats the outer protective layer. That is, the first nanocomposite CX1 distributed in the first optical layer 520 may have any one structure of the structures of the nanocomposites described with reference to FIGS. 1A to 1C and 3A to 3C. Accordingly, detailed description of the nanocomposite CX1 will be omitted.

For example, the first nanocomposite CX1 distributed in the first optical layer 520 may include one kind selected from the blue, green and red nanocomposites. Here, the light passing through the first optical layer 520 may have an emission spectrum in only one wavelength band among the blue, green and red wavelength bands.

As another example, the first nanocomposite CX1 distributed in the first optical layer 520 may include at least two kinds among the blue, green and red nanocomposites. For example, the first nanocomposite CX1 distributed in the first optical layer 520 may be constituted by a plurality of green nanocomposites and a plurality of red nanocomposites.

As another example, the first nanocomposite CX1 distributed in the first optical layer 520 may include a multi-color nanocomposite. The multi-color nanocomposite, which is the first nano light-emitting bodies disposed in the first wax particle, may include at least two kinds selected from the blue, green and red nano light-emitting bodies. For example, the multi-color nanocomposite may include the green nano light-emitting body and the red nano light-emitting body.

The first optical layer 520 may include an optical pattern formed on a surface thereof. A shape of the optical pattern may be variously adjusted according to a function of the optical member 501. The optical pattern may include a light diffusion pattern, a light collection pattern, a light emitting pattern, or the like. The shape of the optical pattern will be described with reference to FIGS. 4C to 4G.

While not shown, the first optical layer 520 may further include diffusion beads that diffuse light. The kind of the diffusion beads is not particularly limited, and any diffusion beads that are conventionally used in the art may be used with no limitation.

On the other hand, an optical layer including the diffusion beads may be formed on the base substrate 510 as a separate layer from the first optical layer 520. The optical layer including the diffusion beads may be formed on one surface of the base substrate 510 on which the first optical layer 520 is formed, or the other surface opposite to the one surface.

Referring to FIG. 4B, an optical member 502 according to another embodiment of the present invention includes a base substrate 510, a first optical layer 520 and a second optical layer 530. The first optical layer 520 includes a first nanocomposite CX1, and the second optical layer 530 includes a second nanocomposite CX2. The first nanocomposite CX1 includes a first wax particle and at least one first nano light-emitting body, and the second nanocomposite CX2 includes a second wax particle and at least one second nano light-emitting body.

Since the optical member 502 described with reference to FIG. 4B is similar to the optical member 501 described with reference to FIG. 4A except that the second optical layer 530 is further included, detailed overlapping description thereof will be omitted.

The second optical layer 530 is formed on the other surface opposite to the one surface of the base substrate 510 on which the first optical layer 520 is formed. The second optical layer 530 includes a polymer resin, and the second nanocomposite CX2 distributed in the polymer resin.

In the second nanocomposite CX2, the second wax particle is formed of a wax-based compound. The at least one second nano light-emitting body is disposed in the second wax particle. Since the second nanocomposite CX2 is substantially the same as the first nanocomposite CX1 described with reference to FIG. 4A, detailed overlapping description will be omitted.

For example, when all of the first nanocomposites CX1 have an emission peak in the same wavelength band and all of the second nanocomposites CX2 have an emission peak in the same wavelength band, the first nanocomposites CX1 and the second second nanocomposites CX2 may have emission peaks in different wavelength bands.

When a wavelength of the light generated from the first nanocomposite CX1 is shorter than a wavelength of the light generated from the second nanocomposite CX2, since a part of the light generated from the first nanocomposite CX1 excites the second nano light-emitting bodies included in the second nanocomposite CX2, the second nanocomposite CX2 may be excited by the part of the light generated from the first nanocomposite CX1 as well as the light provided by the light source. That is, the second nanocomposite CX2 may receive sufficient light from the first nanocomposite CX1 and the light source to be excited. Further, as the light generated from the light source primarily arrives at the first optical layer 520, the first nanocomposite CX1 can receive higher energy from the light source than the second optical layer 530, and thus power density of the light generated from the first nanocomposite CX1 can be maximized.

For example, when a path of the light is in a direction from the first optical layer 520 toward the second optical layer 530, the first nanocomposite CX1 may be a green nanocomposite, and the second nanocomposite CX2 may be a red nanocomposite.

As another example, the first nanocomposite CX1 may include at least two kinds of nanocomposites, and the second nanocomposite CX2 may include one kind of nanocomposite. For example, the first nanocomposite CX1 may include a green nanocomposite and a red nanocomposite, and the second nanocomposite CX2 may include a green nanocomposite.

As another example, the first nanocomposite CX1 and/or the second nanocomposite CX2 may include a multi-color nanocomposite. For example, the multi-color nanocomposite may include a green nano light-emitting body and a red nano light-emitting body.

While the first optical layer 520 and the second optical layer 530 are shown in FIGS. 4A and 4B to have flat surfaces, at least one of the first and second optical layers 520 and 530 may include an optical pattern formed on a surface thereof. The optical pattern may be variously formed according to optical properties to be controlled by the optical members 501 and 502. A shape of the optical pattern will be described in detail.

While not shown, the optical member 502 may further include a third optical layer including a third nanocomposite.

The third optical layer may be formed on the first optical layer 520. When the third optical layer is formed on the first optical layer 520, an optical pattern may be formed on the third optical layer.

The third nanocomposite includes a third wax particle, and at least one third nano light-emitting body disposed in the third wax particle. The third nanocomposite may include any one structure of the structures described with reference to FIGS. 1A to 1C and 3A to 3C. That is, the third nanocomposite may include an inner protective layer and/or an outer protective layer. When the third nanocomposite includes the outer protective layer, the third nanocomposite may further include a wax layer that coats the outer protective layer.

Meanwhile, when the optical member 502 further includes the third optical layer, the second optical layer 530 may be omitted.

FIGS. 4C to 4G are views for describing various shapes of the optical pattern.

Referring to FIG. 4A together with FIG. 4B, the optical pattern formed on the surface of the first optical layer 520 may be a continuous pattern 520 a. The continuous pattern 520 a may have a shape in which a plurality of convex sections are continuously connected. Each of the convex sections protrudes in a direction from the base substrate 510 toward the outside of the optical member 502. Heights or widths of the convex sections may be different from each other and may have irregular values. In another embodiment, while not shown, the optical pattern formed on the surface of the first optical layer 520 may have a shape in which a plurality of concave sections are continuously connected. Each of the concave sections is recessed in a direction from the surface of the optical member 502 toward the inside of the optical member 502. Depths or widths of the concave sections may be appropriately adjusted according to necessity, and depths or widths of the concave sections may have irregular values. In another embodiment, the continuous pattern 520 a may have a shape in which the concave sections and the convex sections are combined, or may be an embossing pattern. The continuous pattern 520 a may function as a light diffusion pattern.

On the other hand, the continuous pattern 520 a may include a plurality of segments as shown in FIG. 4D. FIG. 4D is a plan view for describing the segments. Referring to FIG. 4D, the continuous pattern 520 a may include convex sections formed to correspond to the plurality of segments having irregular planar shapes, which are irregularly arranged. Heights, planar shapes and surface areas of the convex sections are not particularly limited, and the heights or surface areas of the convex sections may have irregular values. While not shown, the continuous pattern 520 a may include concave sections formed to correspond to the plurality of segments having irregular planar shapes, which are irregularly arranged.

Referring to FIG. 4E, the optical pattern formed on the surface of the first optical layer 520 may be a discontinuous convex pattern 520 b. In the discontinuous convex pattern 520 b, the convex sections may be disposed apart from each other. The convex sections that constitute the discontinuous convex pattern 520 b may have dot shapes when seen in a plan view. Heights or widths of the convex sections may be different from each other, and may have irregular values.

Referring to FIG. 4F, the optical pattern formed on the surface of the first optical layer 520 may be a discontinuous concave pattern 520 c. In the discontinuous concave pattern 520 c, the concave sections may be disposed apart from each other. Here, the discontinuous concave pattern 520 c may have dot shapes when seen in a plan view. Depths or widths of the concave sections may be different from each other, and depths or widths of the concave sections may have irregular values.

Referring to FIG. 4G, the optical pattern formed on the surface of the first optical layer 520 may be a light collection pattern 520 d. The light collection pattern 520 d includes a plurality of protrusions, and a cross-section of each of the protrusions may have a triangular shape. The protrusions may be continuously arranged in a first direction substantially parallel to a cut surface that defines a cross-section of the triangular shape. For example, each of the protrusions may extend in a second direction perpendicular to the cross-section to have a predetermined height. That is, each of the protrusions may have a triangular column shape having the predetermined height. Unlike this, a height of each of the protrusions may vary in the second direction. In this case, the height of each of the protrusions may vary linearly or non-linearly in the second direction. Further, the height of each of the protrusions may vary in a predetermined period, or may vary irregularly. The heights of the protrusions may vary independently. A vertex angle of each of the protrusions that constitutes the light collection pattern may be about 90°, but may be appropriately adjusted according to necessity. When the height of each of the protrusions varies in the second direction, the vertex angle of each of the protrusions may vary according to the position thereof.

While various shapes of the optical patterns formed on the first optical layer 520 have been described in FIGS. 4C to 4F, the shapes may also be applied to the optical pattern formed on the second optical layer 530. When the optical patterns are formed at each of the first and second optical layers 520 and 530, the optical pattern formed on the first optical layer 520 and the optical pattern formed on the second optical layer 530 may be the same as or different from each other.

While not shown, each of the optical members 501 and 502 described with reference to FIGS. 4A and 4B may further include a light diffusion layer, on which the optical pattern described with reference to FIGS. 4C to 4G is formed, formed on the first optical layer 520.

Unlike this, in the optical member 501 described in FIG. 4A, the light diffusion layer on which the optical pattern described with reference to FIGS. 4C to 4G is formed may be formed on the other surface of the base substrate 510.

As described above, the nanocomposite including the nano light-emitting body coated with the wax particles may be applied to the at least one optical layer of the optical members 501 and 502. As the optical members 501 and 502 are included in the display device, a color gamut of the display device can be widened, and color purity of the color displayed on the display device can be improved. In particular, since the wax particle included in the nanocomposite protects the nano light-emitting body from heat, moisture or ultraviolet light, the optical members 501 and 502 can be stable with respect to the heat, moisture or ultraviolet light without a separate protective layer to protect the optical layer including the nanocomposite.

The optical members 501 and 502 may be used as a light guide plate, a diffusion sheet, a prism sheet, or the like. Unlike this, the optical members 501 and 502 may be used as an optical sheet which is additionally inserted, in addition to the optical sheets generally applied to a backlight unit for a display device.

Hereinafter, the diffusion sheet, the light collection sheet and the light guide plate to which the nanocomposites are applied will be described in detail with reference to the accompanying drawings.

FIGS. 5A to 5I are views for describing embodiments of the diffusion sheet according to the present invention.

Referring to FIG. 5A, a diffusion sheet 1001 according to the embodiment of the present invention includes a base substrate 1100, and a first optical layer 1200 including a first nanocomposite CX1.

The base substrate 1100 is formed of a transparent material. Since the transparent material is substantially the same as described with reference to FIG. 4A, detailed overlapping description will be omitted.

The first optical layer 1200 is formed on one surface of the base substrate 1100. The surface on which the first optical layer 1200 is formed may be the plane of light emission or may be the plane of light incidence.

The first nanocomposite CX1 distributed in the first optical layer 1200 includes a first wax particle and at least one first nano light-emitting body. The first nano light-emitting body is disposed in the first wax particle and coated with the first wax particle. The first nanocomposite CX1 may have any one of structures of the nanocomposites described with reference to FIGS. 1A to 1C and 3A to 3C.

The first nanocomposite CX1 may include at least one kind among the blue nanocomposite, the green nanocomposite and the red nanocomposite. For example, the first nanocomposite CX1 may include a green nanocomposite or a red nanocomposite. Alternatively, the first nanocomposite CX1 may include a plurality of green nanocomposites and a plurality of red nanocomposites. Unlike this, the first nanocomposite CX1 may include a multi-color nanocomposite. For example, the multi-color nanocomposite may include both a red nano light-emitting body and a green nano light-emitting body.

The first optical layer 1200 includes a light diffusion pattern 1210 formed on a surface thereof. Since the light diffusion pattern 1210 is substantially the same as the continuous pattern 520 a described with reference to FIG. 4C, detailed overlapping description will be omitted. Unlike this, the light diffusion pattern 1210 may be the discontinuous convex pattern 520 b described with reference to FIG. 4E or the discontinuous concave pattern 520 c described with reference to FIG. 4F.

Referring to FIG. 5B, a diffusion sheet 1002 according to another embodiment of the present invention includes a base substrate 1100, a first optical layer 1200 and a second optical layer 1300.

The first optical layer 1200 is formed on one surface of the base substrate 1100, and includes a first nanocomposite CX1. The first nanocomposite CX1 includes a first wax particle, and at least one first nano light-emitting body disposed in the first wax particle. Since the first optical layer 1200 is substantially the same as described with reference to FIG. 5A, detailed overlapping description thereof will be omitted.

The second optical layer 1300 is formed on the other surface opposite to the one surface on which the first optical layer 1200 is formed, and includes a second nanocomposite CX2. The second nanocomposite CX2 includes a second wax particle, and at least one second nano light-emitting body disposed in the second wax particle. The second nanocomposite CX2 may have any one of structures of the nanocomposites described with reference to FIGS. 1A to 1C and 3A to 3C.

The second nanocomposite CX2 and the first nanocomposite CX1 may have the same structure or different structures. For example, when the first nanocomposite CX1 has the structure described with reference to FIG. 1A, the second nanocomposite CX2 may have the structure described with reference to FIG. 3A. Alternatively, the first and second nanocomposites CX1 and CX2 may both have the same structure described with reference to FIG. 1B.

The second nanocomposite CX2 may include at least one kind among the blue nanocomposite, the green nanocomposite and the red nanocomposite. For example, the second nanocomposite CX2 may include a green nanocomposite or a red nanocomposite. Alternatively, the second nanocomposite CX2 may include a plurality of green nanocomposites and a plurality of red nanocomposites. Unlike this, the second nanocomposite CX2 may include a multi-color nanocomposite.

Meanwhile, the second nanocomposite CX2 may have an emission peak in a different wavelength band from a wavelength band to which the emission peak of the first nanocomposite CX1 belongs. Here, FWHM at the emission peak of the first nanocomposite CX1 may be about 70 nm or less. Preferably, the FWHM may be about 50 nm or less, and more preferably, about 40 nm or less. The FWHM may be similarly applied to the second nanocomposite CX2.

For example, when the first nanocomposite CX1 includes a green nanocomposite, the second nanocomposite CX2 may include a red nanocomposite. Here, the second nanocomposite CX2 may further include a green nanocomposite.

As another example, when the first nanocomposite CX1 includes a green nanocomposite, the second nanocomposite CX2 may include a multi-color nanocomposite including a green nano light-emitting body and a red nano light-emitting body.

The second optical layer 1300 includes a light diffusion pattern 1310 formed on a surface thereof. Since the light diffusion pattern 1310 is substantially the same as the continuous pattern 520 a described with reference to FIG. 4C, detailed overlapping description thereof will be omitted. Unlike this, the light diffusion pattern 1310 may be the same as the discontinuous convex pattern 520 b described with reference to FIG. 4E or discontinuous concave pattern 520 c described with reference to FIG. 4F.

While FIG. 5B shows that the light diffusion pattern 1310 of the second optical layer 1300 is a continuous pattern having substantially the same structure as the light diffusion pattern 1210 of the first optical layer 1200, the light diffusion patterns 1210 and 1310 may be continuous patterns having different structures from each other.

Referring to FIG. 5C, a diffusion sheet 1003 according to another embodiment of the present invention includes a base substrate 1100, a first optical layer 1200, a second optical layer 1302 and an intermediate layer 1400.

The first optical layer 1200 is formed on one surface of the base substrate 1100, and includes a first nanocomposite CX1. Since the first optical layer 1200 is substantially the same as described with reference to FIG. 5A, detailed overlapping description thereof will be omitted.

The second optical layer 1302 is formed on the other surface opposite to the one surface of the base substrate 1100 on which the first optical layer 1200 is formed, and includes a second nanocomposite CX2. Since the second optical layer 1302 is substantially the same as described with reference to FIG. 5B except that the surface of the second optical layer 1302 is a flat surface, detailed overlapping description thereof will be omitted. While the second optical layer 1302 is shown to have the flat surface, the second optical layer 1301 may further include the light diffusion pattern 1310, which is substantially the same as described with reference to FIG. 5B.

The intermediate layer 1400 is disposed between the first and second optical layers 1200 and 1302, and includes a third nanocomposite CX3. For example, the intermediate layer 1400 may be disposed between the base substrate 1100 and the second optical layer 1302.

The third nanocomposite CX3 includes a third wax particle, and at least one nano light-emitting body disposed in the third wax particle. The third nanocomposite CX3 may have any one of the structures of the nanocomposites described with reference to FIGS. 1A to 1C and 3A to 3C. Simultaneously, the third nanocomposite CX3 may include at least one kind among the blue nanocomposite, the green nanocomposite and the red nanocomposite. Unlike this, the third nanocomposite CX3 may include a multi-color nanocomposite.

Meanwhile, the third nanocomposite CX3 may have an emission peak in a wavelength band different from the emission peaks of the first and second nanocomposites CX1 and CX2. For example, the first nanocomposite CX1 may include a blue nanocomposite, the second nanocomposite CX2 may include a red nanocomposite, and the third nanocomposite CX3 may include a green nanocomposite. Here, third nanocomposite CX3 may further include a red nanocomposite in addition to the green nanocomposite.

Referring to FIG. 5D, a diffusion sheet 1004 according to another embodiment of the present invention includes a base substrate 1100, a first optical layer 1200, a second optical layer 1302 and an intermediate layer 1402.

The first optical layer 1200 is formed on one surface of the base substrate 1100, and includes a first nanocomposite CX1. Since the base substrate 1100 and the first optical layer 1200 are substantially the same as described with reference to FIG. 5A, detailed overlapping description thereof will be omitted.

The second optical layer 1302 is formed on the other surface opposite to the one surface of the base substrate 1100, and includes a second nanocomposite CX2. Since the second optical layer 1302 is substantially the same as described with reference to FIG. 5C except that the second optical layer 1302 is directly formed on the base substrate 1100, detailed overlapping description thereof will be omitted.

The intermediate layer 1402 is formed between the base substrate 1100 and the first optical layer 1200. The intermediate layer 1402 includes a third nanocomposite CX3. Since the intermediate layer 1402 is substantially the same as the intermediate layer 1400 described with reference to FIG. 5C except for a disposition position, detailed overlapping description thereof will be omitted.

In embodiments of the present invention, the first nanocomposite CX1 may include a blue nanocomposite, the second nanocomposite CX2 may include a red nanocomposite, and the third nanocomposite CX3 may include a green nanocomposite. Here, each of the first to third nanocomposites CX1, CX2 and CX3 may further include any one of the blue, red and green nanocomposites, in addition to the major nanocomposite that constitutes the nanocomposite.

While FIG. 5D shows the case in which a surface of the second optical layer 1302 is a flat surface, the second optical layer 1302 may further include the light diffusion pattern 1310 described with reference to FIG. 5B.

Referring to FIG. 5E, a diffusion sheet 1005 according to another embodiment of the present invention includes a base substrate 1100, a first optical layer 1202 and a light diffusion layer 1500.

The first optical layer 1202 is formed on one surface of the base substrate 1100, and includes a first nanocomposite CX1. Since the first optical layer 1202 is substantially the same as the first optical layer 1200 described with reference to FIG. 5A except that a surface of the first optical layer 1202 is a flat surface, detailed overlapping description thereof will be omitted.

The light diffusion layer 1500 is formed on the other surface opposite to the one surface of the base substrate 1100 on which the first optical layer 1202 is formed. The light diffusion layer 1500 includes a light diffusion pattern 1510 formed on a surface thereof. The light diffusion pattern 1510 may be a pattern that is substantially the same as the continuous pattern 520 a described with reference to FIG. 4C. Unlike this, the light diffusion pattern 1510 may be any one of the discontinuous convex pattern 520 b described with reference to FIG. 4E and the discontinuous concave pattern 520 c described with reference to FIG. 4F. The light diffusion layer 1500 may not include a nanocomposite but function simply to diffuse light.

While FIG. 5E shows that a surface of the first optical layer 1202 is a flat surface, the optical pattern described with reference to FIGS. 4C, and 4E to 4G may also be formed on the surface of the first optical layer 1202.

Referring to FIG. 5F, a diffusion sheet 1006 according to another embodiment of the present invention includes a base substrate 1100, a first optical layer 1204 and a light diffusion layer 1500.

The first optical layer 1204 is substantially the same as the first optical layer 1202 described with reference to FIG. 5E except that the first optical layer 1204 is disposed between the base substrate 1100 and the light diffusion layer 1500. Accordingly, detailed overlapping description thereof will be omitted.

The light diffusion layer 1500 is formed on the first optical layer 1204. The light diffusion layer 1500 is a layer that does not include a nanocomposite but serves simply to diffuse light. Since the light diffusion layer 1500 is substantially the same as described with reference to FIG. 5E, detailed overlapping description thereof will be omitted.

Referring to FIG. 5G, a diffusion sheet 1007 according to another embodiment of the present invention includes a base substrate 1100, a first optical layer 1204, a second optical layer 1302 and a light diffusion layer 1500.

The first optical layer 1204 is disposed on one surface of the base substrate 1100, and includes a first nanocomposite CX1. The light diffusion layer 1500 is formed on the first optical layer 1204, and includes the light diffusion pattern 1510. The light diffusion layer 1500 is a layer that does not include a nanocomposite but serves simply to diffuse light. The first optical layer 1204 and the light diffusion layer 1500 are substantially the same as described with reference to FIG. 5F. Accordingly, detailed overlapping description thereof will be omitted.

The second optical layer 1302 is disposed on the other surface opposite to the one surface of the base substrate 1100 on which the first optical layer 1204 is formed, and includes a second nanocomposite CX2. The second optical layer 1302 is substantially the same as described with reference to FIG. 5D. Accordingly, detailed overlapping description thereof will be omitted.

Referring to FIG. 5H, a diffusion sheet 1008 according to another embodiment of the present invention includes a base substrate 1100, a first optical layer 1204, a second optical layer 1302, a first light diffusion layer 1500 and a second light diffusion layer 1600.

Since the diffusion sheet 1008 is substantially the same as the diffusion sheet 1007 described with reference to FIG. 5G except that the second light diffusion layer 1600 is further included, detailed overlapping description thereof will be omitted. The first light diffusion layer 1500 of FIG. 5H is the same layer as the light diffusion layer of FIG. 5G, and serves to diffuse light.

The second light diffusion layer 1600 is formed on the second optical layer 1302 to oppose the first light diffusion layer 1500. The second light diffusion layer 1600 includes a light diffusion pattern 1610 formed on a surface thereof, and is a layer that does not include a nanocomposite but serves simply to diffuse light. The light diffusion pattern 1610 may be any one of the optical patterns described with reference to FIGS. 4C, and 4E to 4G.

Referring to FIG. 5I, a diffusion sheet 1009 according to another embodiment of the present invention includes a base substrate 1100, a first optical layer 1200 and a light collecting layer 1700.

The first optical layer 1200 is formed on one surface of the base substrate 1100. Since the first optical layer 1200 includes the light diffusion pattern 1210 formed on the surface thereof and is substantially the same as described with reference to FIG. 5A, detailed overlapping description thereof will be omitted.

The light collecting layer 1700 is formed on the other surface opposite to the one surface of the first optical layer 1200. The light collecting layer 1700 includes a light collection pattern 1710 formed on a surface thereof. Since the light collection pattern 1710 is substantially the same as the optical pattern described with reference to FIG. 4G, detailed overlapping description thereof will be omitted.

As described with reference to FIGS. 5A to 5I, the nanocomposites described with reference to FIGS. 1A to 1C and 3A to 3C may be variously applied to the diffusion sheet. Since the diffusion sheet according to the present invention can convert the light provided from the light source to provide the light to a display panel using the nanocomposite, color purity and color reproducibility of the display device can be improved.

FIGS. 6A to 6D are views for describing embodiments of a light collection sheet according to the present invention.

Referring to FIG. 6A, a light collection sheet 2001 according to the embodiment of the present invention includes a base substrate 2100, a light collecting layer 2200 and a first optical layer 2300.

The base substrate 2100 is formed of a transparent material. The transparent material is substantially the same as the transparent material that forms the base substrate 1100 of the diffusion sheet 1001 described with reference to FIG. 5A. Accordingly, detailed overlapping description thereof will be omitted.

The light collecting layer 2200 is formed on one surface of the base substrate 2100. The light collecting layer 2200 includes a light collection pattern 2210 formed on a surface thereof. The light collection pattern 2210 may be substantially the same as the optical pattern described with reference to FIG. 4G. The light collection pattern 2210 is formed to have a cross-sectional shape such that the light entering from the base substrate 2100 is refracted in a vertical direction. Since the cross-sectional shape is the same as the shape described with reference to FIG. 4G, detailed overlapping description thereof will be omitted.

The first optical layer 2300 is formed on the other surface opposite to the one surface on which the light collecting layer 2200 is formed. The first optical layer 2300 includes a first nanocomposite CX1. The first nanocomposite CX1 includes a first wax particle, and at least one first nano light-emitting body disposed in the first wax particle. The first nanocomposite CX1 may have any one of the structures of the nanocomposites described with reference to FIGS. 1A to 1C and 3A to 3C. For example, the first nanocomposite CX1 may include at least one kind selected from the blue, green and red nanocomposites. Unlike this, the first nanocomposite CX1 may include a multi-color nanocomposite.

The first optical layer 2300 may include an optical pattern formed on a surface thereof. The optical pattern may have any one of the structures described with reference to FIGS. 4C to 4F. Accordingly, detailed overlapping description thereof will be omitted.

While not shown, the light collection sheet 2001 may further include a second optical layer disposed between the first optical layer 2300 and the base substrate 2100, or between the light collecting layer 2200 and the base substrate 2100. Here, the second optical layer may include a second nanocomposite including a second wax particle, and at least one second nano light-emitting body disposed in the second wax particle.

Referring to FIG. 6B, a light collection sheet 2002 according to another embodiment of the present invention includes a base substrate 2100, a first optical layer 2300 and a light collecting layer 2200.

The light collection sheet 2002 is substantially the same as the light collection sheet 2001 described with reference to FIG. 6A except that the first optical layer 2300 is disposed between the base substrate 2100 and the light collecting layer 2200. Accordingly, detailed overlapping description thereof will be omitted.

While not shown, the light collection sheet 2002 may further include a second optical layer disposed between the first optical layer 2300 and the base substrate 2100. Here, the second optical layer may include a second nanocomposite.

Referring to FIG. 6C, a light collection sheet 2003 according to another embodiment of the present invention includes a base substrate 2100 and a light collecting layer 2202.

The light collecting layer 2202 is formed on one surface of the base substrate 2100, and includes a first nanocomposite CX1. The light collecting layer 2202 has the light collection pattern 2210 formed on a surface thereof. Since the first nanocomposite CX1 is substantially the same as described with reference to FIG. 6A, detailed overlapping description thereof will be omitted.

While not shown, the light collection sheet 2003 may further include an optical layer formed on the other surface opposite to the one surface on which the light collecting layer 2202 is formed, or formed between the base substrate 2100 and the light collecting layer 2202. Here, the optical layer may include a second nanocomposite.

Referring to FIG. 6D, a light collection sheet 2004 according to another embodiment of the present invention includes a base substrate 2100, a light collecting layer 2202 in which the first nanocomposite CX1 is distributed, and a first optical layer 2400.

The light collection sheet 2004 is substantially the same as the light collection sheet 2003 described with reference to FIG. 6C except that the first optical layer 2400 is further included. Accordingly, detailed overlapping description thereof will be omitted.

The first optical layer 2400 is formed on the other surface opposite to the one surface of the base substrate 2100 on which the light collecting layer 2202 is formed. The first optical layer 2400 includes a light diffusion pattern 2410 formed on a surface thereof. Since the light diffusion pattern 2410 is substantially the same as the continuous pattern 520 a described with reference to FIG. 4C, detailed overlapping description thereof will be omitted. Unlike this, the light diffusion pattern 2410 may be the same pattern as the optical pattern described with reference to FIGS. 4E and 4F.

While not shown, the light collection sheet 2004 may further include a second optical layer formed between the base substrate 2100 and the first optical layer 2400. The second optical layer may include a second nanocomposite.

As described with reference to FIGS. 6A to 6D, the nanocomposites described with reference to FIGS. 1A to 1C and 3A to 3C may be variously applied to the light collection sheet. Since the light collection sheet according to the present invention can convert the light provided from the light source to provide the light to the display panel using the nanocomposite, color purity and color reproducibility of the color displayed on the display device can be improved.

FIGS. 7A to 7C are views for describing embodiments of a light guide plate according to the present invention.

Referring to FIG. 7A, a light guide plate 3001 according to the embodiment of the present invention includes a base substrate 3100, a light emitting pattern 3200 and a first optical layer 3300.

The base substrate 3100 is formed of a transparent material. The transparent material may be, for example, a polymethylmethacrylate (PMMA) resin, a polycarbonate (PC) resin, or the like, but it is not limited thereto.

The light emitting pattern 3200 is formed on one surface of the base substrate 3100. A surface of the base substrate 3100 on which the light emitting pattern 3200 is formed may be a reflective section of the light guide plate 3001. When a section of the light guide plate 3001 facing the light source is referred to as a light entering section of the light guide plate 3001, light emitted from the light source and guided to the base substrate 3100 through the light entering section may be reflected by the reflective section, and then emitted to the outside through the light exiting section opposite to the reflective section. The light emitting pattern 3200 may have various shapes such as a convex pattern, a concave pattern, or the like, or may be a pattern additionally formed on one surface of the base substrate 3100. Unlike this, the light emitting pattern 3200 may be a pattern formed by partially patterning the one surface of the base substrate 3100.

The first optical layer 3300 is formed on the other surface opposite to the one surface on which the light emitting pattern 3200 is formed. That is, a section of the base substrate 3100 on which the first optical layer 3300 is formed may be a light exiting section of the light guide plate 3001. The first optical layer 3300 includes a first nanocomposite CX1. The first nanocomposite CX1 may have any one of the structures of the nanocomposites described with reference to FIGS. 1A to 1C and 3A to 3C. Simultaneously, the first nanocomposite CX1 may include at least one selected from the blue, green and red nanocomposites. Unlike this, the first nanocomposite CX1 may include a multi-color nanocomposite. While not shown, the first optical layer 3300 may have substantially the same pattern as the light emitting pattern 3200.

While FIG. 7A shows that only the first optical layer 3300 is formed on one surface of the base substrate 3100, a second optical layer including a second nanocomposite may be formed between the base substrate 3100 and the first optical layer 3300. Unlike this, the second optical layer may be formed between the light emitting pattern 3200 and the base substrate 3100.

Referring to FIG. 7B, a light guide plate 3002 according to another embodiment of the present invention includes a base substrate 3100, a light emitting pattern 3210, and a first optical layer 3300 in which the first nanocomposite CX1 is distributed.

The light guide plate 3002 is substantially the same as the light guide plate 3001 described with reference to FIG. 7A except that the light emitting pattern 3210 includes the second nanocomposite CX2. Accordingly, detailed overlapping description thereof will be omitted. While not shown, the first optical layer 3300 may further include substantially the same pattern as the light emitting pattern described with reference to FIG. 7A.

The light emitting pattern 3210 includes the second nanocomposite CX2. The second nanocomposite CX2 includes a second wax particle, and at least one second nano light-emitting body disposed in the second wax particle.

The second nanocomposite CX2 may have any one of the structures of the nanocomposites described with reference to FIGS. 1A to 1C and 3A to 3C. Simultaneously, the second nanocomposite CX2 may include at least one kind among the blue, green and red nanocomposites, or may include a multi-color nanocomposite. The second nanocomposite CX2 may have a different emission peak from the emission peak of the first nanocomposite CX1. For example, the second nanocomposite CX2 may include a green nanocomposite, and the first nanocomposite CX1 may include a red nanocomposite.

While not shown, the light guide plate 3002 may further include a second optical layer disposed between the first optical layer 3300 and the base substrate 3100. Here, the second optical layer may include a third nanocomposite different from the first and second nanocomposites CX1 and CX2. The third nanocomposite includes a third wax particle, and at least one third nano light-emitting body disposed in the third wax particle.

Referring to FIG. 7C, a light guide plate 3003 according to another embodiment of the present invention includes a base substrate 3100 and a light emitting pattern 3200.

The light emitting pattern 3200 is substantially the same as described with reference to FIG. 7A, and the base substrate 3100 includes the first nanocomposite CX1. The first nanocomposite CX1 is substantially the same as described with reference to FIG. 7A.

While not shown, an optical layer including a second nanocomposite may be formed on the other surface opposite to the one surface of the base substrate 3100 on which the light emitting pattern 3200 is formed. Unlike this, the optical layer may be formed between the base substrate 3100 and the light emitting pattern 3200.

As described with reference to FIGS. 7A to 7C, the nanocomposites described with reference to FIGS. 1A to 1C and 3A to 3C may be variously applied to the light guide plate. Since the light guide plate according to the present invention can convert the light provided from the light source to provide the light to the display panel using the nanocomposite, color purity and color reproducibility of the display device can be improved.

[Backlight Unit]

FIGS. 8 and 9 are views for describing a backlight unit according to an embodiment of the present invention.

Referring to FIG. 8, a backlight unit 5001 according to the embodiment of the present invention includes a light source 5100, a light guide plate 5200, a reflective plate 5300, a diffusion sheet 5400, a first light collection sheet 5510 and a second light collection sheet 5520.

A white light emitting module or a blue light emitting module may be used as the light source 5100.

The white light emitting module may include a blue light emitting chip configured to generate blue light, and a photoconversion layer configured to coat the blue light emitting chip. That is, since the photoconversion layer absorbs and/or converts blue light generated from the blue light emitting chip, the white light emitting module can finally generate white light. The photoconversion layer may include a phosphor including yttrium aluminum garnet (YAG) or the like, or a nano light-emitting body including quantum dots or the like. Green quantum dots may be used as the nano light-emitting body. Unlike this, the photoconversion layer may include the nanocomposites described with reference to FIGS. 1A to 1C and 3A to 3C.

The blue light emitting module includes a blue light emitting chip configured to generate blue light. That is, an observer can see the blue light emitted from the blue light emitting chip of the blue light emitting module as it is.

The light guide plate 5200 may be disposed adjacent to the light source 5100, the light generated from the light source 5100 may enter the light guide plate 5200, and the light emitted from the light guide plate 5200 may enter the diffusion sheet 5400. The light guide plate 5200 may include any one of the light guide plates 3001, 3002 and 3003 according to the present invention described with reference to FIGS. 7A to 7C.

The reflective plate 5300 is disposed to face a lower section of the light guide plate 5200, i.e., a reflective section of the light guide plate 5200, and the light emitted through the reflective section of the light guide plate 5200 is reflected again toward the light guide plate 5200 to increase use efficiency of the light.

The diffusion sheet 5400 is disposed on the light guide plate 5200, and the light emitted from the light guide plate 5200 can be diffused. The diffusion sheet 5400 may include any one of diffusion sheets 1001 to 1009 described with reference to FIGS. 5A to 5I.

The first light collection sheet 5510 is disposed on the diffusion sheet 5400, and a light collection pattern including a plurality of protrusions described with reference to FIG. 4G is formed on an upper surface of the first light collection sheet 5510. The second light collection sheet 5520 is disposed on the first light collection sheet 5510, and a plurality of protrusions having substantially the same shape as the protrusions formed on the first light collection sheet 5510 are formed on an upper surface of the second light collection sheet 5520. A longitudinal direction of the protrusions formed at the first light collection sheet 5510 may cross a longitudinal direction of the protrusions formed on the second light collection sheet 5520 at a predetermined angle. In this case, a crossing angle of the longitudinal directions of the protrusions may be about 90°. At least one of the first and second light collection sheets 5510 and 5520 may include any one selected from the light collection sheets 2001 to 2004 described with reference to FIGS. 6A to 6D.

For example, when the white light emitting module is used as the light source 5100, at least one of the light guide plate 5200, the diffusion sheet 5400, and the first and second light collection sheets 5510 and 5520 may include a green nanocomposite and/or a red nanocomposite. Even when color purity of the light generated from the white light emitting module is low, the green nanocomposite and/or the red nanocomposite may be applied to at least one of the light guide plate 5200, the diffusion sheet 5400, and the first and second light collection sheets 5510 and 5520 to improve color purity of the white light provided by the backlight unit 5001.

Meanwhile, even when the white light emitting module configured to provide white light having high color purity is used, a deviation in color coordinates is generated between the light emitted from the light entering section adjacent to the light source and the light emitted from an opposite section of the light guide plate 5200 opposite to the light entering section while passing through the light guide plate 5200, the diffusion sheet 5400, the first and second light collection sheets 5510 and 5520, in particular, the light guide plate 5200. The deviation in color coordinates is generated because light of a specific wavelength is relatively largely scattered while the light moves from the light entering section to the opposite section, the observer recognizes the deviation in color coordinates as a yellowish problem in the opposite section. In addition, color purity and color coordinate uniformity of the display device may be decreased due to characteristics of the material that forms the diffusion sheet 5400, and the first and second light collection sheets 5510 and 5520. The above-mentioned problems can be solved by applying the blue nanocomposite to at least one of the light guide plate 5200, the diffusion sheet 5400 and the light collection sheets 5510 and 5520.

As another example, when the blue light emitting module is used as the light source 5100, at least one of the light guide plate 5200, the diffusion sheet 5400, and the first and second light collection sheets 5510 and 5520 may include a green nanocomposite and a red nanocomposite. That is, even when the light source 5100 generates blue light, since the green nanocomposite and the red nanocomposite generate green light and red light, the observer can recognize the light generated by the backlight unit 5001 as white light.

As another example, when an ultraviolet light emitting module is used as the light source 5100, at least one of the light guide plate 5200, the diffusion sheet 5400, and first and second light collection sheets 5510 and 5520 may include a green nanocomposite, a red nanocomposite and a blue nanocomposite. Here, any one of the light guide plate 5200, the diffusion sheet 5400, and first and second light collection sheets 5510 and 5520 may include all of the green, red and blue nanocomposites. Unlike this, the diffusion sheet 5400 may include a blue nanocomposite, the first light collection sheet 5510 may include a green nanocomposite, and the second light collection sheet 5520 may include a red nanocomposite. Alternatively, any one of the light guide plate 5200, the diffusion sheet 5400, and first and second light collection sheets 5510 and 5520 may include two kinds of nanocomposites among the green, red and blue nanocomposites, and another of the light guide plate 5200, the diffusion sheet 5400, and first and second light collection sheets 5510 and 5520 may include one kind of nanocomposite. For example, the diffusion sheet 5400 may include a blue nanocomposite, and the first light collection sheet 5510 may include green and red nanocomposites. As the green, red and blue nanocomposites applied to the light guide plate 5200, the diffusion sheet 5400, and the first and second light collection sheets 5510 and 5520 absorb the light generated by the ultraviolet light emitting module to generate green light, red light and blue light, the backlight unit 5001 can provide white light to the display panel.

Referring to FIG. 9, a backlight unit 5002 according to another embodiment of the present invention includes a light source 5100, a light guide plate 5200, a reflective plate 5300, an optical sheet 5600, a diffusion sheet 5400, a first light collection sheet 5510 and a second light collection sheet 5520. Since the backlight unit 5002 is substantially the same as the backlight unit 5001 described with reference to FIG. 8 except that the optical sheet 5600 is further included, detailed overlapping description thereof will be omitted.

The optical sheet 5600 includes the nanocomposite, and is additionally included in the backlight unit 5002 independently from the light guide plate 5200, the diffusion sheet 5400, the first light collection sheet 5510 and the second light collection sheet 5520. Here, as the light guide plate 5200, the diffusion sheet 5400, the first light collection sheet 5510 and the second light collection sheet 5520 those conventionally used in the art may be used. That is, as only the optical sheet 5600 including the nanocomposites described with reference to FIGS. 1A to 1C and 3A to 3C is inserted into the backlight unit 5002, a color gamut of the display device can be increased to improve color reproducibility.

According to the above description, as the nanocomposites described with reference to FIGS. 1A to 1C and 3A to 3C are applied to at least one optical sheet among the light guide plate 5200, the diffusion sheet 5400, the first light collection sheet 5510 and the second light collection sheet 5520, or a separate optical sheet independent from the light guide plate 5200, the diffusion sheet 5400, the first light collection sheet 5510 and the second light collection sheet 5520, the backlight units 5001 and 5002 can provide a color filter of the display panel with light having high color purity, and can widen a color gamut of the display device to improve color reproducibility.

Hereinafter, effects of the present invention observed through estimation of the color coordinates and color gamuts of the optical sheets according to embodiments and comparative examples, and the backlight unit and the display device including the same will be described.

Manufacture of Backlight Unit Embodiments 1 to 6 and Comparative Examples 1 to 7 Embodiment 1

A blue light emitting module having an emission peak at about 444 nm was used as a light source, and a light guide plate, a diffusion sheet, a first light collection sheet and a second light collection sheet were manufactured through the following methods and prepared.

(1) Manufacture of Light Guide Plate

After a benzotriazol-based ultraviolet light absorbent (trade name: Tinuvin-329, BASF SE, Germany) at 0.5 wt % and a hindered amine-based photostablizer (trade name: Tinuvin-770, BASF SE, Germany) at 0.5 wt % were mixed with a methylmethacrylate polymer at 100 wt %, a pellet type resin was manufactured using an extruder (inner diameter: 27 mm, L/D: 40, Leistritz Co.), and the resin was extruded using a sheet extruder to manufacture a light guide plate having a thickness of about 0.4 mm.

(2) Manufacture of Diffusion Sheet

First, after 20 mg of wax (trade name: Licowax PED 136 wax, Clariant Gmbh., Switzerland), which is oxidized high density polyethylene wax (oxidized HDPE Wax) serving as wax-based compound, having an acid value of about 30 mg KOH/g was mixed with 1 ml of toluene, a temperature of the wax was raised to about 150° C. and the wax-based compound was dissolved to manufacture a wax solution. After a solution in which about 20 mg of a CdSe-based red nano light-emitting body (trade name: Nanodot-HE-610, QD solution Co. Ltd., Korea) was distributed in 1 ml of toluene was added into and mixed with the wax solution, the solution was cooled to room temperature, and the solution was mixed with urethane acrylate purchased from BASF SE (corporate name, Germany) and a photoinitiator (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, TPO) purchased from BASF SE. The photoinitiator was mixed at about 0.8 wt % with respect to 100 wt % urethane acrylate. Next, the toluene was removed using an evaporator to manufacture a first coating composition in which the urethane acrylate, a red nanocomposite and the photoinitiator were mixed. The first coating composition was applied as a coating and cured on a transparent base substrate (trade name: XU42, Toray Industries, Inc., Japan) formed of a polyester material and having a thickness of about 38 μm to form a light diffusion layer having a shape shown in FIG. 4C on a surface thereof. An average thickness of the light diffusion layer was about 50 μm.

Next, a solution in which about 20 mg of a CdSe-based green nano light-emitting body (trade name: Nanodot-HE-530, QD solution Co. Ltd., Korea) was distributed in 1 ml of toluene was added into and mixed with the wax solution prepared in the process of manufacturing the red nanocomposite, and the solution was cooled to room temperature to be mixed with the urethane acrylate and photoinitiator. Next, the toluene was removed using the evaporator to manufacture a second coating composition in which the urethane acrylate, the photoinitiator and a green nanocomposite were mixed. The second coating composition was applied as a coating and cured on an opposite surface of the base substrate on which the light diffusion layer was formed to form an optical layer. A thickness of the optical layer was about 50 μm.

Accordingly, a diffusion sheet including the base substrate, the light diffusion layer and the optical layer was manufactured.

(3) Manufacture of First and Second Light Collection Sheets

A catalyst (tetra-n-butylphosphoniumbromide) purchased from Nippon Industries Co. Ltd. (corporate name, Japan) was mixed at 0.07 wt % with bis(2,3-epithiopropyl)sulfide at 100 wt %, and the solution was agitated to manufacture a uniformized solution. The uniformized solution was agitated and defoamed, and then filtered through a polytetrafluroroethylene membrane (a PTFE membrane) having a thickness of about 0.5 μm to manufacture a base material. Next, the base material was applied on a PET film having a thickness of about 75 μm and pressed by a forming roller to manufacture a light collection pattern having a height of about 25 μm on the PET film, thereby manufacturing a first light collection sheet.

A second light collection sheet was manufactured through substantially the same process as the method of manufacturing the first light collection sheet.

(4) Manufacture of Backlight Unit

The light guide plate, the diffusion sheet, the first light collection sheet and the second light collection sheet, which were manufactured through the methods described above, were sequentially deposited to assemble a blue light emitting module, and thus a backlight unit according to Embodiment 1 of the present invention was prepared.

Embodiment 2

YAG phosphor purchased from Nichia Corporation (corporate name, Japan) was applied on a blue light emitting chip representing an emission peak at about 444 nm together with an OE-6630 silicon resin (trade name, Dow Corning Corporation, US) and then cured to manufacture a white light emitting module.

Substantially the same backlight unit as Embodiment 1 was prepared as the backlight unit according to Embodiment 2, except that the white light emitting module was used as the light source.

Embodiment 3

First, substantially the same light guide plate as Embodiment 1 was prepared.

A photoinitiator (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, TPO) purchased from BASF SE (corporate name, Germany) was mixed at about 0.7 wt % with urethane acrylate at 100 wt % purchased from BASF SE, and a coat thereof was applied and cured on a transparent base substrate (trade name: XU42, Toray Industries, Inc., Japan) formed of a polyester material and having a thickness of about 38 μm to form a light diffusion layer having an average thickness of about 50 μm and a shape as shown in FIG. 4 c on the surface thereof, thereby preparing a diffusion sheet.

In the first light collection sheet of Embodiment 1, a second coating composition including a green nanocomposite described in Embodiment 1 was applied as a coating and cured on the other surface opposite to the one surface of the PET film on which the light collection pattern was formed to form an optical layer having an average thickness of about 5 μm and a shape as shown in FIG. 4 d on a surface thereof, thereby preparing a first light collection sheet according to Embodiment 3.

In addition, in the second light collection sheet of Embodiment 1, a first coating composition including a red nanocomposite described in Embodiment 1 was applied as a coating and cured on the other surface opposite to the one surface of the PET film on which the light collection pattern was formed to form an optical layer having an average thickness of about 5 μm and a shape as shown in FIG. 4 d on a surface thereof, thereby preparing a second light collection sheet according to Embodiment 3.

The light guide plate, the diffusion sheet, the first light collection sheet and the second light collection sheet, which were prepared as described above, were assembled to the blue light emitting module representing an emission peak at about 444 nm to prepare a backlight unit according to Embodiment 3 of the present invention.

Embodiment 4

Substantially the same backlight unit as that of Embodiment 3 was prepared as a backlight unit according to Embodiment 4 of the present invention, except that the white light emitting module described Embodiment 2 was used as the light source.

Embodiment 5

First, the diffusion sheet of Embodiment 3 and the first light collection sheet and the second light collection sheet of Embodiment 1 were prepared.

In addition, the second coating composition including the green nanocomposite described in Embodiment 1 was applied as a coating and cured on the one surface of the light guide plate of Embodiment 1 to form the first optical layer having a thickness of about 5 μm. Next, the first coating composition including the red nanocomposite described in Embodiment 1 was applied as a coating and cured on the first optical layer to form the second optical layer having a thickness of about 5 μm. Accordingly, a light guide plate according to Embodiment 5 of the present invention including the base substrate, and the first and second optical layers was manufactured.

The light guide plate, the diffusion sheet, and the first and second light collection sheets, which were prepared as described above, were assembled with the blue light emitting module representing an emission peak at about 444 nm to prepare a backlight unit according to Embodiment 5 of the present invention.

Embodiment 6

The same backlight unit as that of Embodiment 5 was prepared as a backlight unit of Embodiment 6 of the present invention, except that the white light emitting module was used as the light source.

Comparative example 1

Substantially the same backlight unit as that of Embodiment 1 was prepared as a backlight unit according to Comparative example 1, except that the white light emitting module described in Embodiment 2 was used as the light source and the diffusion sheet included in the backlight unit according to Embodiment 3 was used.

Comparative Example 2

Substantially the same backlight unit as that of Embodiment 1 was prepared as a backlight unit according to Comparative example 2, except that, in the diffusion sheet, a red nano light-emitting body (trade name: Nanodot-HE-610, QD solution Co. Ltd., Korea) was used instead of the red nanocomposite, and a green nano light-emitting body (trade name: Nanodot-HE-530, QD solution Co. Ltd., Korea) was used instead of the green nanocomposite.

Comparative Example 3

Substantially the same backlight unit as that of Comparative example 2 was prepared as a backlight unit according to Comparative example 3, except that the white light emitting module was used as the light source.

Comparative Example 4

Substantially the same backlight unit as that of Embodiment 3 was prepared as a backlight unit according to Comparative example 4, except that the green nano light-emitting body (trade name: Nanodot-HE-530, QD solution Co. Ltd., Korea) was used in the first light collection sheet instead of the green nanocomposite, and the red nano light-emitting body (trade name: Nanodot-HE-610, QD solution Co. Ltd., Korea) was used in the second light collection sheet instead of the red nanocomposite.

Comparative Example 5

Substantially the same backlight unit as that of Comparative example 2 was prepared as a backlight unit according to Comparative example 5, except that the white light emitting module was used as the light source.

Comparative Example 6

Substantially the same backlight unit as that of Embodiment 5 was prepared as a backlight unit according to Comparative example 6, except that, in the light guide plate, the red nano light-emitting body (trade name: Nanodot-HE-610, QD solution Co. Ltd., Korea) was used instead of the red nanocomposite and the green nano light-emitting body (trade name: Nanodot-HE-530, QD solution Co. Ltd., Korea) was used instead of the green nanocomposite.

Comparative Example 7

Substantially the same backlight unit as that of Comparative example 6 was prepared as a backlight unit according to Comparative example 7, except that the white light emitting module was used as the light source.

Experiment 2 Estimation of Color Coordinates and Color Gamut of Display Device

Each of the backlight units according to Embodiments 1 to 6 and Comparative examples 1 to 7 was assembled to an iPhone 4 (trade name, Apple Inc., US) display panel to prepare display devices 1 to 6 and comparative devices 1 to 7.

A color gamut, brightness and color coordinates (red, green, and blue) were measured with respect to the display devices 1 to 6 and the comparative devices 1 to 7 using SR-3AR (trade name, TOPCON Corporation, Japan) serving as a spectroradiometer. The red, green and blue color coordinates were obtained by causing the iPhone 4 display panels to display red, green and blue and then recording color coordinates represented by the spectroradiometer. The result is shown in the following Table 2.

In Table 2, the red, green and blue color coordinates are represented with respect to a CIE 1931 color coordinate system, and a chromatic ratio is a percentage of an area of a triangle formed by connecting RGB color coordinates of the display devices and comparative devices with respect to a chromatic range with respect to a National Television Systems Committee (NTSC) chromatic range (hereinafter referred to as an NTSC chromatic range).

TABLE 2 Color Color Color Chromatic Brightness coordinates - coordinates - coordinates - Classification ratio (%) (cd/m²) red (CIE 1931) green (CIE 1931) blue (CIE 1931) Display 89.2 350 (0.660, 0.319) (0.205, 0.705) (0.160, 0.123) device 1 Display 78.7 313 (0.652, 0.330) (0.210, 0.650) (0.160, 0.123) device 2 Display 80.4 340 (0.648, 0.325) (0.215, 0.667) (0.160, 0.123) device 3 Display 73.9 310 (0.630, 0.340) (0.220, 0.648) (0.160, 0.123) device 4 Display 84.5 330 (0.648, 0.319) (0.205, 0.689) (0.160, 0.123) device 5 Display 74.7 290 (0.633, 0.342) (0.224, 0.652) (0.160, 0.123) device 6 Comparative 51.3 314 (0.611, 0.354) (0.318, 0.564) (0.160, 0.123) device 1 Comparative 89.2 340 (0.665, 0.323) (0.230, 0.687) (0.160, 0.123) device 2 Comparative 76.9 305 (0.657, 0.336) (0.228, 0.642) (0.160, 0.123) device 3 Comparative 80.2 330 (0.650, 0.334) (0.219, 0.666) (0.160, 0.123) device 4 Comparative 74.0 300 (0.635, 0.355) (0.230, 0.650) (0.160, 0.123) device 5 Comparative 83.9 330 (0.655, 0.319) (0.230, 0.687) (0.160, 0.123) device 6 Comparative 75.5 285 (0.648, 0.336) (0.228, 0.642) (0.160, 0.123) device 7

FIG. 10 is an image for describing a color gamut of a display device including a backlight unit according to Comparative example 1, and FIGS. 11A to 11F are images for describing color gamuts of display devices including backlight units according to Embodiments 1 to 6.

Referring to Table 2 and FIGS. 10 and 11A to 11F, it will be appreciated that the color gamut of the comparative device 1 including the backlight unit according to Comparative example 1 is about 51.3% of the NTSC chromatic range, whereas the color gamuts of the display devices 1 to 6 are about 73.9% to about 89.2% of the NTSC chromatic range, and thus the display devices 1 to 6 have remarkably larger color gamuts than the comparative device 1.

Specifically, comparing the comparative device 1 with the display devices 1 to 6, it will be appreciated that, while the blue color coordinates are substantially similar to each other, red x coordinates of the display devices 1 to 6 are higher than red x coordinates of the comparative device 1. In addition, it will be appreciated that green x coordinates of the display devices 1 to 6 are lower than green x coordinates of the comparative device 1, and green y coordinates of the display devices 1 to 6 are higher than green y coordinates of the comparative device 1.

Referring to the above-mentioned results, it will be appreciated that color purity of red and green of the display devices 1 to 6 is relatively larger than the comparative device 1. That is, even when the same display panel is used, the display device can implement red and green having higher color purity by the backlight units according to Embodiments 1 to 6 than the backlight unit according to Comparative example 1, and a color region that can be implemented by the display device is widened.

Furthermore, it will be appreciated that the display devices 1 to 6 have the brightness substantially equal to or higher than the brightness of the comparative device 1 even when the nanocomposites having the structure in which the nano light-emitting body is coated with the wax particles are distributed.

Meanwhile, it will be appreciated that the color purity of red and green is implemented at substantially the same level as the color purity of red and green of the comparative devices 2 to 7 even when the display devices 1 to 6 include the nanocomposites having the structures in which the nano light-emitting bodies are encapsulated by the wax particles. That is, it will be appreciated that the wax particles are not a factor that decreases quantum efficiency of the nano light-emitting body even when the nano light-emitting body is coated with the wax particles.

Manufacture of Flat Sheets 1 and 2 and Comparative Sheet 1 [Manufacture of Flat Sheet 1]

Wax (trade name: Licowax PED 136 wax, Clariant Gmbh, Switzerland), which is oxidized high density polyethylene wax (oxidized HDPE wax) serving as wax-based compound, having an acid value of about 30 mg KOH/g was mixed with 1 ml of toluene, and then a temperature of the wax was raised to about 150° C. to dissolve the wax-based compound, thereby manufacturing a wax solution. A solution in which about 20 mg of a CdSe-based red nano light-emitting body (trade name: Nanodot-HE-610, QD solution Co. Ltd., Korea) was distributed in 1 ml of toluene was mixed with the wax solution, and then cooled to room temperature to manufacture a cooled solution.

After the cooled solution was mixed with urethane acrylate purchased from BASF SE (corporate name, Germany) and a photoinitiator (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, TPO) purchased from BASF SE, the toluene was removed to manufacture a coating composition. The photoinitiator was mixed at about 0.8 wt % with respect to 100 wt % of urethane acrylate.

The coating composition was applied as a coating and cured on a transparent base substrate (trade name: XU42, Toray Industries, Inc., Japan) formed of a polyester material and having a thickness of about 38 μm to manufacture a flat sheet 1 including an optical layer having a thickness of about 50 μm.

[Manufacture of Flat Sheet 2]

After 20 mg of the wax-based compound was mixed with 1 ml of toluene, the temperature of the mixture was increased to about 150° C. to dissolve the wax-based compound and manufacture the wax solution. After a solution in which about 20 mg of CdSe-based red quantum dots (trade name: Nanodot-HE-606, QD solution Co. Ltd., Korea) was distributed in 1 ml of toluene was mixed with the wax solution, the solution was cooled to room temperature to manufacture a cooled solution in which about 10 mg of particles was distributed in 1 ml of toluene. Here, as the wax-based compound, a wax (trade name: Licowax PED 136 wax, Clariant Gmbh, Switzerland), which is an oxidized high density polyethylene wax (oxidized HDPE wax), having an acid value of about 50 mg KOH/g was used. After the cooled solution was mixed with a solution in which 10 ml of ethanol and 1 ml of TEOS (tetraethoxysilane, Sigma Aldrich Co. LLC., US) were mixed, 2.5 ml of ammonia water having a concentration of 30% was added to form silicon oxide on surfaces of the particles, thereby manufacturing a nanocomposite solution including a nanocomposite.

The nanocomposite solution was centrifugally separated at about 5,000 rpm for about 30 minutes using a high speed centrifugal separator to separate the nanocomposite, the solution was cleaned using ethanol and distilled water, the ethanol and the distilled water were removed using the evaporator to manufacture the nanocomposite in a powder phase, and then the solution was distributed in the toluene again to manufacture a distributed solution.

The distributed solution was mixed with urethane acrylate purchased from BASF SE (corporate name, Germany) and a photoinitiator (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, TPO) purchased from BASF SE, and then the toluene was removed to manufacture a coating composition. The photoinitiator was mixed at about 0.8 wt % with respect to 100 wt % of urethane acrylate.

The coating composition was applied as a coating and cured on a transparent base substrate (trade name: XU42, Toray Industries, Inc., Japan) formed of a polyester material and having a thickness of about 38 μm to manufacture a flat sheet 2 including an optical layer having a thickness of about 50 μm.

[Manufacture of Comparative Sheet 1]

After a solution in which about 20 mg of a CdSe-based red nano light-emitting body (trade name: Nanodot-HE-610, QD solution Co. Ltd., Korea) was distributed in 1 ml of toluene was mixed with urethane acrylate purchased from BASF SE (corporate name, Germany) and a photoinitiator (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, TPO) purchased from BASF SE, the toluene was removed to manufacture a coating composition. The photoinitiator was mixed at about 0.8 wt % with respect to 100 wt % of urethane acrylate.

The coating composition was applied as a coating and cured on a transparent base substrate (trade name: XU42, Toray Industries, Inc., Japan) formed of a polyester material having a thickness of about 38 μm to manufacture a comparative sheet 1 including an optical layer having a thickness of about 50 μm.

Experiment 3 Estimation of Light Stability and Heat/Moisture Stability

The flat sheets 1 and 2 and the comparative sheet 1, which were manufactured as described above, were measured using an absolute quantum efficiency measurement device (trade name: C9920-02, HAMAMATSU Photonics K. K., Japan). Next, ultraviolet (UV) light having a central wavelength of 365 nm was radiated at a radiation intensity of about 1.4 mW/cm² for 480 hours, i.e., under severe conditions of about 2,419.2 J/cm², and then second quantum efficiency (QYT2, unit: %) was measured. A difference between the first quantum efficiency and the second quantum efficiency (ΔQY1=QYT1−QYT2, unit: %) was calculated to estimate ultraviolet light stability of the red nanocomposite of the flat sheets 1 and 2 and the red nano light-emitting body of the comparative sheet 1.

In addition, after the first quantum efficiency (QYT 1, unit: %) was measured with respect to the flat sheets 1 and 2 and the comparative sheet 1, the sheets were exposed to the thermo-hygrostat for 480 hours under severe conditions of a temperature of 85° C. and a relative humidity of 85%, and then a third quantum efficiency (QYT3, unit: %) was measured. A difference between the first quantum efficiency and the third quantum efficiency (ΔQY2=QYT1−QYT3, unit: %) was measured to estimate heat/moisture stability with respect to the red nanocomposite of the flat sheets 1 and 2 and the red nano light-emitting body of the comparative sheet 1.

The light stability estimation result and the heat/moisture stability estimation result are represented in the following Table 3.

In Table 3, due to the light stability and heat/moisture stability of the comparative sheet 1, no emission occurred after exposure to the severe condition, and thus the second quantum efficiency and the third quantum efficiency could not be measured. Accordingly, they are represented as “-” in Table 3.

TABLE 3 Quantum Light Heat/moisture efficiency stability stability (QY, %) (ΔQY1, %) (ΔQY2, %) Flat sheet 1 78.1 6 7 Flat sheet 2 75.5 4 5 Comparative 32.5 — — sheet 1

Referring to FIG. 3, it will be appreciated that quantum efficiency of the red nanocomposite included in the flat sheet 1 and the red nanocomposite included in the flat sheet 2 is better than quantum efficiency of that included in the comparative sheet 1. That is, it will be appreciated that the quantum efficiency of the nanocomposites included in the flat sheets 1 and 2 is maintained at about 75% or more even when the same nano light-emitting body as that included in the comparative sheet 1 is used in order to manufacture the flat sheets 1 and 2 and the nanocomposites.

On the other hand, it may be analogized that at least a part of the red nano light-emitting body is damaged during a process of manufacturing the comparative sheet 1, for example, a step of mixing the red nano light-emitting body with urethane acrylate or a step of curing the urethane acrylate.

In particular, it will be appreciated that, in the light stability or heat/moisture stability, a damage level of the nanocomposites of the flat sheets 1 and 2 caused by light, heat and moisture is about 7%, which is very low, even when the nanocomposites are exposed to the severe conditions, and light stability and heat/moisture stability are very good. On the other hand, it will be appreciated that light stability and heat/moisture stability of the red nano light-emitting body is very bad because the second and third quantum efficiency cannot be measured due to non-emission of the red nano light-emitting body after exposure to the manufactured comparative sheet 1 to the severe conditions.

According to the above description, it will be appreciated that the nanocomposite having a structure in which the nano light-emitting body is coated with the wax particles is very stable with respect to light, heat and moisture, and the nanocomposite is not easily damaged due to light, heat or moisture even when the nanocomposite is mixed with a sheet-manufacturing composition such as urethane acrylate and cured to manufacture the sheet.

Manufacture of Backlight Unit Embodiment 7 and Comparative Example 8 Embodiment 7

Substantially the same backlight unit as that of Embodiment 1 was prepared as a backlight unit according to Embodiment 7 of the present invention, except that the light diffusion pattern having the shape shown in FIG. 4 c was formed on the surface of the optical layer of the diffusion sheet.

Comparative Example 8

Substantially the same backlight unit as that of Comparative example 2 was prepared as a backlight unit according to Comparative example 8, except that the light diffusion pattern having the shape shown in FIG. 4 c was further formed on the surface of the optical layer of the diffusion sheet.

Experiment 4 Estimation of Brightness and Color Coordinates Stability

In order to independently perform estimation of ultraviolet light stability and heat/moisture stability, two backlight units according to Embodiment 7 and two backlight units according to Comparative example 8, which were described above, were prepared.

First, with respect to the backlight units according to Embodiment 7 and Comparative example 8, initial brightness and initial color coordinates were measured using SR-3AR (trade name, TOPCON Corporation, Japan) serving as a spectroradiometer.

Next, the backlight units according to Embodiment 7 and Comparative example 8 were selected one by one and the diffusion sheets were separated from the backlight units, and then ultraviolet (UV) light having a central wavelength of 365 nm was radiated to the diffusion sheet at a radiation intensity of about 1.4 mW/cm2 for 480 hours, i.e., under severe conditions of about 2,419.2 J/cm². After the diffusion sheet irradiated with the ultraviolet light was assembled with the blue light emitting module, the light guide plate, and the first and second light collection sheets, final brightness and final color coordinates thereof were measured. The results are represented in Table 4.

In addition, after the diffusion sheets were separated from the other backlight units according to Embodiment 7 and Comparative example 8, the diffusion sheets were left in the thermo-hygrostat under the severe conditions of a temperature of 85° C. and a relative humidity 85% for 480 hours. The diffusion sheets left in the high temperature/high humidity conditions were assembled to the blue light emitting module, the light guide plate, and the first and second light collection sheets again, and then final brightness and final color coordinates thereof were measured. The results are represented in Table 5.

The initial/final brightness and the initial/final color coordinates are average values of the values measured at nine points of the display section on which the light guide plate, the diffusion sheet, and the first and second light collection sheets were deposited, except for a portion of the backlight unit at which the light source was disposed. The 9 points are designated as shown in FIG. 12.

In FIG. 12, a light source is designated by LS, a display section on which a light guide plate, a diffusion sheet, and first and second light collection sheets are deposited is designated by DS, points 1, 2 and 3 in the display section DS adjacent to the light source LS are a light entering section, and points 7, 8 and 9 opposite to the light entering section are a light-facing section. Provided that a length in a lateral direction of the display section DS is referred to as a, and a length in a longitudinal direction is referred to as b, each of the points 1, 2 and 3 is spaced a/6 from a first edge of the display section DS adjacent to the light entering section, and each of the points 7, 8 and 9 is spaced a/6 from a second edge of the display section DS corresponding to the light-facing section. In addition, each of the points 1, 4 and 7 is spaced b/6 from a third edge that connects the first and second edges, and each of the points 3, 6 and 9 is spaced b/6 from a fourth edge facing the third edge. The points 1, 2 and 3 are spaced a/3 from the points 4, 5 and 6, respectively, and the points 4, 5 and 6 are spaced a/3 from the points 7, 8 and 9, respectively. Simultaneously, the points 1, 4 and 7 are spaced b/3 from the points 2, 5 and 8, respectively, and the points 2, 5 and 8 are spaced b/3 from the points 3, 6 and 9, respectively.

In Tables 4 and 5, the initial/final color coordinates are represented with reference to the CIE 1931 color coordinate system.

Ultraviolet Light Stability Test Result

TABLE 4 Initial Initial color Final Final color Backlight brightness coordinates brightness coordinates classification (cd/m²) (CIE 1931) (cd/m²) (CIE 1931) Embodiment 7 6,207 (0.268, 0.273) 6,052 (0.267, 0.271) Comparative 3,502 (0.248, 0.199) 1,885 (0.225, 0.164) example 8

Referring to Table 4, it will be appreciated that the initial brightness of the backlight unit according to Embodiment 7 of the present invention was about 6,207 cd/m², which is about 1.77 times the initial brightness of the backlight unit according to Comparative example 8 of about 3,502 cd/m². In particular, it will be appreciated that the final brightness measured after the ultraviolet light in the severe conditions was applied to the backlight unit according to Embodiment 7 of the present invention was reduced in comparison with the initial brightness by about 150 cd/m², whereas the final brightness of the backlight unit according to Comparative example 8 was reduced by about 1,617 cd/m², which is substantially half of the initial brightness.

In addition, it will be appreciated that, in the initial color coordinates and the final color coordinates of the backlight unit according to Embodiment 7 of the present invention, a difference (Δx) of an x coordinate was about 0.001 and a difference (Δy) of a y coordinate was about 0.002, whereas a difference (Δx) between the initial color coordinates and the final color coordinates of the backlight unit according to Comparative example 8 was 0.023 and a difference (Δy) of a y coordinate was about 0.035.

Heat/Moisture Stability Test Result

TABLE 5 Initial Initial color Final Final color Backlight brightness coordinates brightness coordinates classification (cd/m²) (CIE 1931) (cd/m²) (CIE 1931) Embodiment 7 6,207 (0.268, 0.273) 6,025 (0.263, 0.267) Comparative 3,502 (0.248, 0.199) 1,543 (0.213, 0.155) example 8

Referring to FIG. 5, it will be appreciated that the final brightness measured after severe high temperature and high humidity conditions were applied to the backlight unit according to Embodiment 8 of the present invention was reduced in comparison with the initial brightness by about 182 cd/m2, whereas the final brightness of the backlight unit according to Comparative example 8 was reduced by about 1,959 cd/m2, which is substantially half of the initial brightness.

In addition, it will be appreciated that, in the initial color coordinates and the final color coordinates of the backlight unit according to Embodiment 8 of the present invention, a difference (Δx) of the x coordinate was about 0.005 and a difference (Δy) of the y coordinate was about 0.006, whereas a difference (Δx) between the initial color coordinates and the final color coordinates of the backlight unit according to Comparative example 8 is 0.035 and a difference (Δy) of the y coordinate is about 0.044.

According to the above description, it will be appreciated that, in consideration of the fact that the nano light-emitting body is applied to the diffusion sheet of the backlight unit according to Comparative example 8 and the nanocomposite is applied to the diffusion sheet of the backlight unit according to Embodiment 7 of the present invention, the nanocomposite is not easily damaged during a process of manufacturing the diffusion sheet, and stability with respect to heat, moisture and light is better than that of the nano light-emitting body even in the diffusion sheet.

Manufacture of Backlight Unit Embodiments 8 to 10 Embodiment 8 (1) Manufacture of Light Guide Plate

After a benzotriazol-based ultraviolet light absorbent (trade name: Tinuvin-329, BASF SE, Germany) at 0.5 wt % and a hindered amine-based photostablizer (trade name: Tinuvin-770, BASF SE, Germany) at 0.5 wt % were mixed with a methylmethacrylate polymer at 100 wt %, a pellet type resin was manufactured using an extruder (an inner diameter: 27 mm, L/D: 40, Leistritz. Co.), and the resin was extruded using a sheet extruder to manufacture an optical plate having a thickness of about 0.4 mm. A coating composition including a blue nanocomposite was coated on one surface of the optical plate to form an optical layer having a thickness of about 5 μm to manufacture a light guide plate.

The coating composition was cooled to room temperature after the wax solution was mixed with a solution in which about 20 mg of a blue nano light-emitting body (trade name; Nanodot-HE-480, QD solution Co. Ltd., Korea) was distributed in 1 ml of toluene, and was mixed with urethane acrylate purchased from BASF SE (corporate name, Germany) and a photoinitiator (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, TPO) purchased from BASF SE. The photoinitiator was mixed at about 0.8 wt % with the urethane acrylate at 100 wt %. Next, the solution was manufactured by removing the toluene using an evaporator.

(2) Manufacture of Diffusion Sheet

A photoinitiator (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, TPO) purchased from BASF SE was mixed at about 0.7 wt % with urethane acrylate purchased from BASF SE (corporate name, Germany) at 100 wt %, and applied as a coating and cured on a transparent base substrate (trade name: XU42, Toray Industries, Inc., Japan) formed of a polyester material and having a thickness of about 38 μm to form a light diffusion layer having an average thickness of about 50 μm and a shape shown in FIG. 4 c on a surface thereof, thereby preparing a diffusion sheet.

(3) Manufacture of First and Second Light Collection Sheets

A catalyst (tetra-n-butylphosphoniumbromide) purchased from Nippon Industries Co. Ltd. (corporate name, Japan) was mixed at 0.07 wt % with bis(2,3-epithiopropyl)sulfide at 100 wt % and agitated at room temperature to manufacture a uniformized solution. The uniformized solution was agitated, defoamed, and then filtered through a polytetrafluoroethylene membrane (PTFE membrane) having a thickness of about 0.5 μm to manufacture a base material. Next, the solution was applied on a PET film having a thickness of about 75 μm and pressed by a forming roll to manufacture a light collection pattern having a height of about 25 μm on the PET film, thereby manufacturing a first light collection sheet.

A second light collection sheet was manufactured through substantially the same process as the method of manufacturing the first light collection sheet.

(4) Manufacture of Backlight Unit

The light guide plate, the diffusion sheet, and the first and second light collection sheets, which were prepared as described above, were assembled to a white light emitting module manufactured by applying and curing YAG phosphor purchased from Nichia Corporation (corporate name, Japan) on a blue light emitting chip having an emission peak at about 444 nm together with an OE-6630 silicon resin (trade name, Dow Corning Corporation, US), thereby preparing a backlight unit according to Embodiment 8 of the present invention. Here, the optical layer of the light guide plate was disposed at a light exiting surface of light provided from the light source.

Embodiment 9 (1) Manufacture of Light Guide Plate

After a benzotriazol-based ultraviolet light absorbent (trade name: Tinuvin-329, BASF SE, Germany) at 0.5 wt % and a hindered amine-based photostablizer (trade name: Tinuvin-770, BASF SE, Germany) at 0.5 wt % were mixed with a methylmethacrylate polymer at 100 wt %, a pellet type resin was manufactured using an extruder (inner diameter: 27 mm, L/D: 40, Leistritz. Co.), and then the resin was extruded using a sheet extruder to manufacture an optical plate having a thickness of about 0.4 mm serving as a light guide plate.

(2) Manufacture of Diffusion Sheet

After wax (trade name: Licowax PED 136 wax, Clariant Gmbh, Switzerland) 20 mg, which is oxidized high density polyethylene wax (oxidized HDPE wax) serving as a wax-based compound, having an acid value of about 30 mg KOH/g was mixed with 1 ml of toluene, the solution was increased to a temperature of about 150° C. to dissolve the wax-based compound and manufacture a wax solution. After a solution in which about 20 mg of a CdSe-based blue nano light-emitting body (trade name: Nanodot-HE-480, QD solution Co. Ltd., Korea) was distributed in 1 ml of toluene was added into and mixed with the wax solution, the solution was cooled to room temperature, and mixed with urethane acrylate purchased from BASF SE (corporate name, Germany) and a photoinitiator (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, TPO) purchased from BASF SE. The photoinitiator was mixed at about 0.8% with the urethane acrylate at 100 wt %. Next, the toluene was removed using an evaporator to manufacture a coating composition in which the urethane acrylate, a red nanocomposite and the photoinitiator were mixed. The coating composition was applied as a coating and cured on a transparent base substrate (trade name: XU42, Toray Industries, Inc., Japan) formed of a polyester material and having a thickness of about 38 μm to form a light diffusion layer having a shape as shown in FIG. 4 c on a surface thereof. An average thickness of the light diffusion layer was about 50 μm.

(3) Manufacture of First and Second Light Collection Sheets

Substantially the same first and second light collection sheets as described in Embodiment 8 were prepared.

(4) Manufacture of Backlight Unit

The light guide plate, the diffusion sheet, and the first and second light collection sheets, which were prepared as described above, were assembled to the white light emitting module described in Embodiment 2 to prepare a backlight unit according to Embodiment 9 of the present invention.

Embodiment 10 (1) Manufacture of Light Guide Plate and Diffusion Sheet

Substantially the same light guide plate as described in Embodiment 9 was prepared, and substantially the same diffusion sheet as described in Embodiment 8 was prepared.

(2) Manufacture of First Light Collection Sheet

A catalyst (tetra-n-butylphosphoniumbromide) purchased from Nippon Industries Co. Ltd. (corporate name, Japan) was mixed at 0.07 wt % with bis(2,3-epithiopropyl)sulfide at 100 wt % and agitated at room temperature to manufacture a uniformized solution. The uniformized solution was agitated, defoamed, and filtered through a polytetrafluoroethylene membrane (PTFE membrane) having a thickness of about 0.5 μm to manufacture a base material, and the base material was applied on a PET film having a thickness of about 75 μm and then pressed by a forming roll to manufacture a light collection pattern having a height of about 25 μm on the PET film, thereby manufacturing a first light collection sheet.

(2) Manufacture of Second Light Collection Sheet

After a light collection pattern was formed through substantially the same process as the method of manufacturing the first light collection sheet, a coating composition including the blue nanocomposite, the polyurethane acrylate and the photoinitiator (diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, TPO) described in Embodiment 9 was applied as a coating and cured on an opposite surface of the PET film on which the light collection pattern was formed, and an optical layer having a shape as shown in FIG. 4 d and an average thickness of about 5 μm was formed on the surface thereof to manufacture a second light collection sheet.

(3) Manufacture of Backlight Unit

The light guide plate, the diffusion sheet, and the first and second light collection sheets, which were prepared as described above, were assembled to the white light emitting module to prepare a backlight unit according to Embodiment 10.

Experiment 5 Estimation of Color Coordinate Uniformity

Color coordinates of nine points of the backlight unit were measured as shown in FIG. 12 with respect to the backlight unit according to Comparative example 1 and the backlight units according to Embodiments 8 to 10. The results are represented in Table 6.

In Table 6, Δx represents a difference between a maximum value and a minimum value of x coordinates of the points 1 to 9, and Δy represents a difference between a maximum value and a minimum value of y coordinates of the points 1 to 9.

TABLE 6 Comparative Embodiment Embodiment Embodiment example 1 8 9 10 Point Color coordinates (x, y) 1 (0.297, 0.283) (0.295, 0.282) (0.295, 0.281) (0.294, 0.281) 2 (0.296, 0.281) (0.297, 0.283) (0.295, 0.281) (0.293, 0.278) 3 (0.298, 0.283) (0.299, 0.286) (0.299, 0.285) (0.296, 0.281) 4 (0.302, 0.290) (0.294, 0.283) (0.292, 0.282) (0.289, 0.278) 5 (0.301, 0.288) (0.296, 0.284) (0.294, 0.282) (0.291, 0.279) 6 (0.303, 0.289) (0.299, 0.287) (0.297, 0.285) (0.293, 0.280) 7 (0.311, 0.303) (0.295, 0.287) (0.293, 0.286) (0.289, 0.281) 8 (0.312, 0.303) (0.296, 0.287) (0.293, 0.284) (0.291, 0.281) 9 (0.314, 0.304) (0.298, 0.288) (0.295, 0.285) (0.292, 0.283) Δx 0.018 0.004 0.007 0.007 Δy 0.023 0.006 0.004 0.005

Referring to Table 6, it will be appreciated that, in the backlight unit according to Comparative example 1, the light entering section adjacent to the light source, i.e., the color coordinates of the points 1 to 3, have lower values for x coordinates and y coordinates than the color coordinates of the points 5 to 9 of the light-facing section facing the light entering section. On the other hand, it will be appreciated that, in the backlight units of Embodiments 7 to 9 of the present invention, the color coordinates of the points 1 to 3 had substantially the same numerical values as the color coordinates of the points 7 to 9. That is, it will be appreciated that, in the backlight units according to Embodiments 7 to 9 of the present invention, there is almost no difference in color coordinates between the light entering section and the light-facing section.

Referring to Δx and Δy, it will be appreciated that the values of the backlight units according to Embodiments 7 to 9 are remarkably smaller than the value in Comparative example 1. That is, in the backlight unit according to Comparative example 1, the light-facing section appears yellower to the observer than the light entering section due to a difference in color coordinates between the light entering section and the light-facing section. However, it will be appreciated that the difference in color coordinates of the points 1 to 9 is remarkably reduced by the optical sheet including the blue nanocomposite like the backlight units according to Embodiments 7 to 9. Accordingly, as the blue nanocomposite is applied to at least one of the diffusion sheet, the light guide plate and the light collection sheet, the color coordinates of the backlight unit can be uniformly adjusted as a whole.

While the present invention has been described with reference to the exemplary embodiments, it will be apparent to those skilled in the art that the present invention can be variously modified and changed without departing from the spirit and the scope of the present invention disclosed in the accompanying claims. 

What is claimed is:
 1. A nanocomposite comprising: a wax particle; at least one nano light-emitting body disposed in the wax particle; and an inner protective layer formed of silicon oxide and configured to coat the nano light-emitting body.
 2. The nanocomposite according to claim 1, wherein the inner protective layer coats one nano light-emitting body.
 3. The nanocomposite according to claim 2, wherein the nano light-emitting bodies disposed in the wax particle have an emission peak in the same wavelength band.
 4. The nanocomposite according to claim 2, wherein at least two of the nano light-emitting bodies disposed in the wax particle have emission peaks in different wavelength bands.
 5. The nanocomposite according to claim 1, wherein the inner protective layer coats the two or more nano light-emitting bodies.
 6. The nanocomposite according to claim 5, wherein each of the nano light-emitting bodies has an emission peak in the same wavelength band.
 7. The nanocomposite according to claim 5, wherein at least two of the nano light-emitting bodies have emission peaks in different wavelength bands.
 8. The nanocomposite according to claim 1, further comprising an outer protective layer formed of silicon oxide and coating a surface of the wax particle.
 9. The nanocomposite according to claim 8, further comprising a wax layer formed on a surface of the outer protective layer and including a wax-based compound.
 10. A nanocomposite comprising: a wax particle; at least one nano light-emitting body disposed in the wax particle; and an outer protective layer formed of silicon oxide and coating the wax particle.
 11. The nanocomposite according to claim 10, wherein at least two of the nano light-emitting bodies in the wax particle have emission peaks in different wavelength bands.
 12. The nanocomposite according to claim 10, further comprising a wax layer formed on a surface of the outer protective layer and including a wax-based compound.
 13. An optical member comprising: a base substrate; and a first optical layer disposed on one surface of the base substrate and in which at least one first nanocomposite is distributed, wherein the first nanocomposite comprises: a first wax particle; and at least one first nano light-emitting body disposed in the first wax particle.
 14. The optical member according to claim 13, further comprising a second optical layer disposed on the other surface of the base substrate opposite to the one surface and in which at least one second nanocomposite is distributed, wherein the second nanocomposite comprises: a second wax particle; and at least one second nano light-emitting body disposed in the second wax particle.
 15. The optical member according to claim 13, further comprising a third optical layer disposed on the first optical layer and in which at least one third nanocomposite is distributed, wherein the third nanocomposite comprises: a third wax particle; and at least one third nano light-emitting body disposed in the third wax particle.
 16. The optical member according to claim 13, wherein at least one of the first and second nano light-emitting bodies is coated with an inner protective layer formed of silicon oxide.
 17. The optical member according to claim 13, wherein at least one of the first and second wax particles is coated with an outer protective layer formed of silicon oxide.
 18. The optical member according to claim 15, wherein at least one of the first to third wax particles is coated with an outer protective layer formed of silicon oxide.
 19. The optical member according to claim 17, wherein at least one of the first and second nanocomposites further comprises a wax layer formed of a wax-based compound and coating the outer protective layer.
 20. The optical member according to claim 18, wherein at least one of the first to third nanocomposites further comprises a wax layer formed of a wax-based compound and coating the outer protective layer.
 21. The optical member according to claim 13, wherein at least one of the first and second optical layers comprises an optical pattern.
 22. The optical member according to claim 15, wherein at least one of the first to third optical layers comprises an optical pattern.
 23. The optical member according to claim 13, wherein the first optical layer includes a plurality of first nanocomposites, and each of the first nanocomposites includes at least one selected from a red nano light-emitting body; a green nano light-emitting body; and a blue nano light-emitting body disposed in the first wax particle.
 24. The optical member according to claim 13, further comprising a light diffusion layer formed on the first optical layer.
 25. The optical member according to claim 14, further comprising a light diffusion layer formed on the second optical layer.
 26. A diffusion sheet comprising: a base substrate; and a first optical layer formed on one surface of the base substrate, including at least one first nanocomposite, and having a light diffusion pattern formed on a surface thereof, wherein the first nanocomposite comprises: a first wax particle; and at least one first nano light-emitting body disposed in the first wax particle.
 27. The diffusion sheet according to claim 26, wherein a plurality of first nano light-emitting bodies included in the first wax particle have an emission peak in the same wavelength band.
 28. The diffusion sheet according to claim 16, wherein at least two first nano light-emitting bodies included in the first wax particle have emission peaks in different wavelength bands.
 29. The diffusion sheet according to claim 26, further comprising a second optical layer including at least one second nanocomposite disposed on the other surface opposite to the one surface, wherein the second nanocomposite comprises: a second wax particle; and at least one second nano light-emitting body disposed in the second wax particle.
 30. The diffusion sheet according to claim 29, wherein a plurality of second nano light-emitting bodies included in the second wax particle have an emission peak in the same wavelength band.
 31. The diffusion sheet according to claim 29, wherein at least two second nano light-emitting bodies included in the second wax particle have emission peaks in different wavelength bands.
 32. The diffusion sheet according to claim 29, wherein a light diffusion pattern is formed on a surface of the second optical layer.
 33. The diffusion sheet according to claim 29, wherein a peak wavelength of light generated from the first nano light-emitting body is larger than a peak wavelength of light generated from the second nano light-emitting body.
 34. The diffusion sheet according to claim 33, wherein the first nano light-emitting body has an emission peak at 600 nm to 660 nm, and the second nano light-emitting body has an emission peak at 520 nm to 560 nm.
 35. The diffusion sheet according to claim 29, further comprising an intermediate layer disposed between the base substrate and the second optical layer, the intermediate layer including at least one third nanocomposite, wherein the third nanocomposite comprises: a third wax particle; and at least one third nano light-emitting body disposed in the third wax particle.
 36. The diffusion sheet according to claim 26, further comprising an intermediate layer disposed between the base substrate and the first optical layer, the intermediate layer including at least one third nanocomposite, wherein the third nanocomposite comprises: a third wax particle; and at least one third nano light-emitting body disposed in the third wax particle.
 37. The diffusion sheet according to claim 26, further comprising a second optical layer disposed on the other surface of the base substrate opposite to the one surface, second optical layer having a light collection pattern formed on a surface thereof.
 38. A diffusion sheet comprising: a base substrate; a light diffusion layer formed on one surface of the base substrate; and a first optical layer formed on the other surface of the base substrate opposite to the one surface, the first optical layer including at least one first nanocomposite, wherein the first nanocomposite comprises: a first wax particle; and at least one first nano light-emitting body disposed in the first wax particle.
 39. The diffusion sheet according to claim 38, wherein a plurality of first nano light-emitting bodies included in the first wax particle have an emission peak in the same wavelength band.
 40. The diffusion sheet according to claim 38, further comprising a second optical layer disposed on the first optical layer, the second optical layer including at least one second nanocomposite, wherein the second nanocomposite comprises: a second wax particle; and at least one second nano light-emitting body disposed in the second wax particle.
 41. The diffusion sheet according to claim 40, wherein the first nano light-emitting body and the second nano light-emitting body have emission peaks in different wavelength bands.
 42. The diffusion sheet according to claim 38, further comprising a light diffusion layer formed on the first optical layer.
 43. A light collection sheet comprising: a base substrate; and a light collection pattern disposed on the base substrate, light collection pattern including a nanocomposite having at least one nano light-emitting body disposed in a wax particle.
 44. A light collection sheet comprising: a base substrate; a light collection pattern disposed on one surface of the base substrate; and an optical layer disposed on the other surface of the base substrate opposite to the one surface, the optical layer including a nanocomposite, wherein the nanocomposite comprises: a wax particle; and at least one nano light-emitting body disposed in the wax particle.
 45. The light collection sheet according to claim 44, wherein a light diffusion pattern is formed on a surface of the optical layer.
 46. A backlight unit comprising: a light source; a diffusion sheet configured to receive light from the light source; and a light collection sheet disposed on the diffusion sheet, wherein at least one of the diffusion sheet and the light collection sheet comprises at least one nanocomposite including a wax particle and at least one nano light-emitting body disposed in the wax particle.
 47. The backlight unit according to claim 46, wherein the light source comprises a blue light emitting module.
 48. The backlight unit according to claim 46, wherein the wax particle of each of the plurality of nanocomposites comprises at least one selected from a red nano light-emitting body and a green nano light-emitting body. 